pw.x

Input File Description

Program: pw.x / PWscf / Quantum Espresso

TABLE OF CONTENTS

INTRODUCTION

&CONTROL

calculation | title | verbosity | restart_mode | wf_collect | nstep | iprint | tstress | tprnfor | dt | outdir | wfcdir | prefix | lkpoint_dir | max_seconds | etot_conv_thr | forc_conv_thr | disk_io | pseudo_dir | tefield | dipfield | lelfield | lberry | gdir | nppstr | nberrycyc

&SYSTEM

ibrav | celldm | A | B | C | cosAB | cosAC | cosBC | nat | ntyp | nbnd | nelec | tot_charge | ecutwfc | ecutrho | nr1 | nr2 | nr3 | nr1s | nr2s | nr3s | nosym | noinv | occupations | degauss | smearing | nspin | noncolin | starting_magnetization | nelup | neldw | multiplicity | tot_magnetization | ecfixed | qcutz | q2sigma | xc_type | lda_plus_u | Hubbard_alpha | Hubbard_U | starting_ns_eigenvalue(m,ispin,I) | U_projection_type | edir | emaxpos | eopreg | eamp | angle1 | angle2 | constrained_magnetization | fixed_magnetization | B_field | lambda | report | lspinorb | assume_isolated

&ELECTRONS

electron_maxstep | conv_thr | mixing_mode | mixing_beta | mixing_ndim | mixing_fixed_ns | diagonalization | ortho_para | diago_thr_init | diago_cg_maxiter | diago_david_ndim | diago_full_acc | efield | startingpot | startingwfc | tqr

&IONS

ion_dynamics | phase_space | pot_extrapolation | wfc_extrapolation | remove_rigid_rot | ion_temperature | tempw | tolp | delta_t | nraise | refold_pos | upscale | bfgs_ndim | trust_radius_max | trust_radius_min | trust_radius_ini | w_1 | w_2 | num_of_images | opt_scheme | CI_scheme | first_last_opt | temp_req | ds | k_max | k_min | path_thr | use_masses | use_freezing | fe_step | g_amplitude | fe_nstep | sw_nstep

&CELL

cell_dynamics | press | wmass | cell_factor | press_conv_thr | cell_dofree

&PHONON

modenum | xqq

ATOMIC_SPECIES

X | Mass_X | PseudoPot_X

ATOMIC_POSITIONS

X | x | y | z | if_pos(1) | if_pos(2) | if_pos(3) |

K_POINTS

nks | xk_x | xk_y | xk_z | wk | nk1 | nk2 | nk3 | sk1 | sk2 | sk3

CELL_PARAMETERS

v1 | v2 | v3

CLIMBING_IMAGES

index1, index2, ... indexN

CONSTRAINTS

nconstr | constr_tol | constr_type | constr(1) | constr(2) | constr(3) | constr(4) | constr_target

COLLECTIVE_VARS

ncolvar | colvar_tol | colvar_type | colvar(1) | colvar(2) | colvar(3) | colvar(4)

OCCUPATIONS

f_inp1 | f_inp2

INTRODUCTION

Input data format: { } = optional, [ ] = it depends, | = or

All quantities whose dimensions are not explicitly specified are in
RYDBERG ATOMIC UNITS

Structure of the input data:
===============================================================================

&CONTROL
...
/

&SYSTEM
...
/

&ELECTRONS
...
/

[ &IONS
...
/ ]

[ &CELL
...
/ ]

[ &PHONON
...
/ ]

ATOMIC_SPECIES
X Mass_X PseudoPot_X
Y Mass_Y PseudoPot_Y
Z Mass_Z PseudoPot_Z

ATOMIC_POSITIONS { alat | bohr | crystal | angstrom }
in all cases except calculation = 'neb' or 'smd' :
X 0.0 0.0 0.0 {if_pos(1) if_pos(2) if_pos(3)}
Y 0.5 0.0 0.0
Z O.0 0.2 0.2
if calculation = 'neb' .OR. 'smd' :
first_image
X 0.0 0.0 0.0 {if_pos(1) if_pos(2) if_pos(3)}
Y 0.5 0.0 0.0
Z O.0 0.2 0.2
{ intermediate_image 1
X 0.0 0.0 0.0
Y 0.9 0.0 0.0
Z O.0 0.2 0.2
intermediate_image ...
X 0.0 0.0 0.0
Y 0.9 0.0 0.0
Z O.0 0.2 0.2 }
last_image
X 0.0 0.0 0.0
Y 0.7 0.0 0.0
Z O.0 0.5 0.2

K_POINTS { tpiba | automatic | crystal | gamma }
if (gamma)
nothing to read
if (automatic)
nk1, nk2, nk3, k1, k2, k3
if (not automatic)
nks
xk_x, xk_y, xk_z, wk

[ CELL_PARAMETERS { cubic | hexagonal }
v1(1) v1(2) v1(3)
v2(1) v2(2) v2(3)
v3(1) v3(2) v3(3) ]

[ OCCUPATIONS
f_inp1(1) f_inp1(2) f_inp1(3) ... f_inp1(10)
f_inp1(11) f_inp1(12) ... f_inp1(nbnd)
[ f_inp2(1) f_inp2(2) f_inp2(3) ... f_inp2(10)
f_inp2(11) f_inp2(12) ... f_inp2(nbnd) ] ]

[ CLIMBING_IMAGES
list of images, separated by a comma ]

[ CONSTRAINTS
nconstr { constr_tol }
constr_type(.) constr(1,.) constr(2,.) [ constr(3,.) constr(4,.) ] { constr_target(.) } ]

[ COLLECTIVE_VARS
ncolvar { colvar_tol }
colvar_type(.) colvar(1,.) colvar(2,.) [ colvar(3,.) colvar(4,.) ] ]

Namelist: CONTROL

calculation CHARACTER
Default: 'scf'
a string describing the task to be performed:
'scf', 'nscf', 'bands', 'phonon', 'relax', 'md',
'vc-relax', 'vc-md', 'neb', 'smd', 'metadyn'
(vc = variable-cell).
title CHARACTER
Default: ' '
reprinted on output.
verbosity CHARACTER
'high' | 'default' | 'low' | 'minimal'
restart_mode CHARACTER
Default: 'from_scratch'
'from_scratch'  : from scratch
NEB and SMD only: the starting path is obtained
with a linear interpolation between the images
specified in the ATOMIC_POSITIONS card.
Note that in the linear interpolation
periodic boundary conditions ARE NON USED.

'restart' : from previous interrupted run
wf_collect LOGICAL
Default: .FALSE.
This flag controls the way wavefunctions are stored to disk :

.TRUE. collect wavefunctions from all processors and store
them into the output data directory outdir/prefix.save

.FALSE. do not collect wavefunctions, leave them in temporary
local files (one per processor). The resulting format
will be readable only by jobs running on the same
number of processors and pools. Useful if you do not
need the wavefunction or if you want to reduce the I/O
or the disk occupancy.
nstep INTEGER
Default: 1 if calculation = 'scf', 'nscf', 'bands'; 0 if calculation = 'neb', 'smd'; 50 for the other cases
number of ionic + electronic steps
iprint INTEGER
Default: write only at convergence
band energies are written every iprint iterations
tstress LOGICAL
calculate stress. Set to .TRUE. if calculation='vc-md'
tprnfor LOGICAL
print forces. Set to .TRUE. if calculation='relax','md','vc-md'
dt REAL
Default: 20.D0
time step for molecular dynamics, in Rydberg atomic units
(1 a.u.=4.8378 * 10^-17 s : beware, CP and FPMD codes use
Hartree atomic units, half that much!!!)
outdir CHARACTER
Default: value of the ESPRESSO_TMPDIR environment variable if set; current directory ('./') otherwise
input, temporary, output files are found in this directory,
see also 'wfcdir'
wfcdir CHARACTER
Default: same as outdir
this directory specifies where to store files generated by
each processor (*.wfc{N}, *.igk{N}, etc.). The idea here is
to be able to separately store the largest files, while
the files necessary for restarting still go into 'outdir'
(for now only works for stand alone PW )
prefix CHARACTER
Default: 'pwscf'
prepended to input/output filenames:
prefix.wfc, prefix.rho, etc.
lkpoint_dir LOGICAL
Default: .true.
If .false. it does not open a subdirectory for each k_point
in the prefix.save directory.
max_seconds REAL
Default: 1.D+7, or 150 days, i.e. no time limit
jobs stops after max_seconds CPU time
etot_conv_thr REAL
Default: 1.0D-4
convergence threshold on total energy (a.u) for ionic
minimization: the convergence criterion is satisfied
when the total energy changes less than etot_conv_thr
between two consecutive scf steps.
See also forc_conv_thr - both criteria must be satisfied
forc_conv_thr REAL
Default: 1.0D-3
convergence threshold on forces (a.u) for ionic
minimization: the convergence criterion is satisfied
when all components of all forces are smaller than
forc_conv_thr.
See also etot_conv_thr - both criteria must be satisfied
disk_io CHARACTER
Default: 'default'
Specifies the amount of disk I/O activity
'high': save all data at each SCF step

'default': save wavefunctions at each SCF step unless
there is a single k-point per process

'low' : store wfc in memory, save only at the end

'none': do not save wfc, not even at the end

If restarting from an interrupted calculation, the code
will try to figure out what is available on disk. The
more you write, the more complete the restart will be.
pseudo_dir CHARACTER
Default: value of the $ESPRESSO_PSEUDO environment variable if set; '$HOME/espresso/pseudo/' otherwise
directory containing pseudopotential files
tefield LOGICAL
Default: .FALSE.
If .TRUE. a sawlike potential simulating an electric field
is added to the bare ionic potential. See variables
edir, eamp, emaxpos, eopreg for the form and size of
the added potential.
dipfield LOGICAL
Default: .FALSE.
If .TRUE. and tefield=.TRUE. a dipole correction is also
added to the bare ionic potential - implements the recipe
of L. Bengtsson, PRB 59, 12301 (1999). See variables edir,
emaxpos, eopreg for the form of the correction, that must
be used only in a slab geometry, for surface calculations,
with the discontinuity in the empty space.
lelfield LOGICAL
Default: .FALSE.
If .TRUE. a homogeneous finite electric field described
through the modern theory of the polarization is applied.
This is different from "tefield=.true." !
lberry LOGICAL
Default: .FALSE.
If .TRUE. perform a Berry phase calculation
See the header of PW/bp_c_phase.f90 for documentation
gdir INTEGER
For Berry phase calculation: direction of the k-point
strings in reciprocal space. Allowed values: 1, 2, 3
1=first, 2=second, 3=third reciprocal lattice vector
For calculations with finite electric fields
(lelfield==.true.), gdir is the direction of the field
nppstr INTEGER
For Berry phase calculation: number of k-points to be
calculated along each symmetry-reduced string
The same for calculation with finite electric fields
(lelfield==.true.)
nberrycyc INTEGER
Default: 1
In the case of a finite electric field  ( lelfield == .TRUE. )
it defines the number of iterations for converging the
wavefunctions in the electric field Hamiltonian, for each
external iteration on the charge density

Namelist: SYSTEM

ibrav INTEGER
Status: REQUIRED
Bravais-lattice index:

ibrav structure celldm(2)-celldm(6)

0 "free", see above not used
1 cubic P (sc) not used
2 cubic F (fcc) not used
3 cubic I (bcc) not used
4 Hexagonal and Trigonal P celldm(3)=c/a
5 Trigonal R celldm(4)=cos(alpha)
6 Tetragonal P (st) celldm(3)=c/a
7 Tetragonal I (bct) celldm(3)=c/a
8 Orthorhombic P celldm(2)=b/a,celldm(3)=c/a
9 Orthorhombic base-centered(bco) celldm(2)=b/a,celldm(3)=c/a
10 Orthorhombic face-centered celldm(2)=b/a,celldm(3)=c/a
11 Orthorhombic body-centered celldm(2)=b/a,celldm(3)=c/a
12 Monoclinic P celldm(2)=b/a,celldm(3)=c/a,
celldm(4)=cos(ab)
13 Monoclinic base-centered celldm(2)=b/a,celldm(3)=c/a,
celldm(4)=cos(ab)
14 Triclinic celldm(2)= b/a,
celldm(3)= c/a,
celldm(4)= cos(bc),
celldm(5)= cos(ac),
celldm(6)= cos(ab)

For P lattices: the special axis (c) is the z-axis, one basal-plane
vector (a) is along x, the other basal-plane vector (b) is at angle
gamma for monoclinic, at 120 degrees for trigonal and hexagonal
lattices, at 90 degrees for cubic, tetragonal, orthorhombic lattices

sc simple cubic
====================
v1 = a(1,0,0), v2 = a(0,1,0), v3 = a(0,0,1)

fcc face centered cubic
====================
v1 = (a/2)(-1,0,1), v2 = (a/2)(0,1,1), v3 = (a/2)(-1,1,0).

bcc body entered cubic
====================
v1 = (a/2)(1,1,1), v2 = (a/2)(-1,1,1), v3 = (a/2)(-1,-1,1).

simple hexagonal and trigonal(p)
====================
v1 = a(1,0,0), v2 = a(-1/2,sqrt(3)/2,0), v3 = a(0,0,c/a).

trigonal(r)
===================
for these groups, the z-axis is chosen as the 3-fold axis, but the
crystallographic vectors form a three-fold star around the z-axis,
and the primitive cell is a simple rhombohedron. The crystallographic
vectors are:
v1 = a(tx,-ty,tz), v2 = a(0,2ty,tz), v3 = a(-tx,-ty,tz).
where c=cos(alpha) is the cosine of the angle alpha between any pair
of crystallographic vectors, tc, ty, tz are defined as
tx=sqrt((1-c)/2), ty=sqrt((1-c)/6), tz=sqrt((1+2c)/3)

simple tetragonal (p)
====================
v1 = a(1,0,0), v2 = a(0,1,0), v3 = a(0,0,c/a)

body centered tetragonal (i)
================================
v1 = (a/2)(1,-1,c/a), v2 = (a/2)(1,1,c/a), v3 = (a/2)(-1,-1,c/a).

simple orthorhombic (p)
=============================
v1 = (a,0,0), v2 = (0,b,0), v3 = (0,0,c)

bco base centered orthorhombic
=============================
v1 = (a/2,b/2,0), v2 = (-a/2,b/2,0), v3 = (0,0,c)

face centered orthorhombic
=============================
v1 = (a/2,0,c/2), v2 = (a/2,b/2,0), v3 = (0,b/2,c/2)

body centered orthorhombic
=============================
v1 = (a/2,b/2,c/2), v2 = (-a/2,b/2,c/2), v3 = (-a/2,-b/2,c/2)

monoclinic (p)
=============================
v1 = (a,0,0), v2= (b*cos(gamma), b*sin(gamma), 0), v3 = (0, 0, c)
where gamma is the angle between axis a and b

base centered monoclinic
=============================
v1 = ( a/2, 0, -c/2),
v2 = (b*cos(gamma), b*sin(gamma), 0),
v3 = ( a/2, 0, c/2),
where gamma is the angle between axis a and b

triclinic
=============================
v1 = (a, 0, 0),
v2 = (b*cos(gamma), b*sin(gamma), 0)
v3 = (c*cos(beta), c*(cos(alpha)-cos(beta)cos(gamma))/sin(gamma),
c*sqrt( 1 + 2*cos(alpha)cos(beta)cos(gamma)
- cos(alpha)^2-cos(beta)^2-cos(gamma)^2 )/sin(gamma) )
where alpha is the angle between axis b and c
beta is the angle between axis a and c
gamma is the angle between axis a and b
celldm(i), i=1,6 REAL
See: ibrav
Crystallographic constants - see description of ibrav variable.

* alat = celldm(1) is the lattice parameter "a" (in BOHR)
* only needed celldm (depending on ibrav) must be specified
* if ibrav=0 only alat = celldm(1) is used (if present)
A, B, C, cosAB, cosAC, cosBC REAL
Traditional crystallographic constants (a,b,c in ANGSTROM),
cosab = cosine of the angle between axis a and b
specify either these OR celldm but NOT both.
If ibrav=0 only alat = a is used (if present)
nat INTEGER
Status: REQUIRED
number of atoms in the unit cell
ntyp INTEGER
Status: REQUIRED
number of types of atoms in the unit cell
nbnd INTEGER
Default: for an insulator, nbnd = number of valence bands (nbnd=nelec/2, see below for nelec); for a metal, 20% more (minimum 4 more)
number of electronic states (bands) to be calculated.
Note that in spin-polarized calculations the number of
k-point, not the number of bands per k-point, is doubled
nelec REAL
Default: the same as ionic charge (neutral cell)
number of electron in the unit cell
(may be noninteger if you wish)

A compensating jellium background is inserted
to remove divergences if the cell is not neutral
tot_charge INTEGER
Default: 0
total system charge. Used only if nelec is unspecified,
otherwise it is ignored.
ecutwfc REAL
Status: REQUIRED
kinetic energy cutoff (Ry) for wavefunctions
ecutrho REAL
Default: 4 * ecutwfc
kinetic energy cutoff (Ry) for charge density and potential
May be larger ( for ultrasoft PP ) or somewhat smaller
( but not much smaller ) than the default value. Note that
if you have norm-conserving PP only, setting it to a larger
value than the default is a waste of time.
nr1, nr2, nr3 INTEGER
three-dimensional FFT mesh (hard grid) for charge
density (and scf potential). If not specified
the grid is calculated based on the cutoff for
charge density (see also "ecutrho")
nr1s, nr2s, nr3s INTEGER
three-dimensional mesh for wavefunction FFT and for the smooth
part of charge density ( smooth grid ).
Coincides with nr1, nr2, nr3 if ecutrho = 4 * ecutwfc ( default )
nosym LOGICAL
Default: .FALSE.
if (.TRUE.) symmetry is not used. Note that a k-point grid
provided in input is used "as is"; an automatically generated
k-point grid will contain only points in the irreducible BZ
of the lattice. Use with care in low-symmetry large cells
if you cannot afford a k-point grid with the correct symmetry.
noinv LOGICAL
Default: .FALSE.
if (.TRUE.) disable the usage of time reversal (q => -q)
symmetry in k-point generation
occupations CHARACTER
'smearing':     gaussian smearing for metals
requires a value for degauss

'tetrahedra' : for metals and DOS calculation
(see PRB49, 16223 (1994))
Requires uniform grid of k-points,
automatically generated (see below)
Not suitable (because not variational) for
force/optimization/dynamics calculations

'fixed' : for insulators with a gap

'from_input' : The occupation are read from input file.
Presently works only with one k-point
(LSDA allowed).
degauss REAL
Default: 0.D0 Ry
value of the gaussian spreading (Ry) for brillouin-zone
integration in metals.
smearing CHARACTER
Default: 'gaussian'
'gaussian', 'gauss':
ordinary Gaussian spreading (Default)

'methfessel-paxton', 'm-p', 'mp':
Methfessel-Paxton first-order spreading
(see PRB 40, 3616 (1989)).

'marzari-vanderbilt', 'cold', 'm-v', 'mv':
Marzari-Vanderbilt cold smearing
(see PRL 82, 3296 (1999))

'fermi-dirac', 'f-d', 'fd':
smearing with Fermi-Dirac function
nspin INTEGER
Default: 1
nspin = 1 :  non-polarized calculation (default)

nspin = 2 : spin-polarized calculation, LSDA
(magnetization along z axis)

nspin = 4 : spin-polarized calculation, noncollinear
(magnetization in generic direction)
DO NOT specify nspin in this case;
specify "noncolin=.TRUE." instead
noncolin LOGICAL
Default: .false.
if .true. the program will perform a noncollinear calculation.
starting_magnetization(i), i=1,ntyp REAL
starting spin polarization (values between -1 and 1)
on atomic type 'i' in a spin-polarized calculation.
Breaks the symmetry and provides a starting point for
self-consistency. The default value is zero, BUT a value
MUST be specified for AT LEAST one atomic type in spin
polarized calculations. Note that if start from zero
initial magnetization, you will get zero final magnetization
in any case. If you desire to start from an antiferromagnetic
state, you may need to define two different atomic species
corresponding to sublattices of the same atomic type.
If you fix the magnetization with "nelup/neldw" or with
"multiplicity" or with "tot_magnetization", you should
not specify starting_magnetization.
If you are restarting from a previous run, or from an
interrupted run, starting_magnetization is ignored.
nelup, neldw REAL
number of spin-up and spin-down electrons, respectively
Note that this fixes the final value of the magnetization.
The sum must yield nelec that must also be specified
explicitly in this case. Not valid for spin-unpolarized
or noncollinear calculations, only for LSDA. Obsolescent:
use multiplicity or tot_magnetization instead.
multiplicity INTEGER
Default: 0 [unspecified]
spin multiplicity (2s+1). 1 is singlet, 2 for doublet etc.
Note that this fixes the final value of the magnetization.
if unspecified or a non-zero value is specified in nelup/neldw
then multiplicity variable is ignored.
Do not specify both multiplicity and tot_magnetization.
tot_magnetization INTEGER
Default: -1 [unspecified]
majority spin - minority spin (nelup - neldw).
if unspecified or a non-zero value is specified in nelup/neldw
then tot_magnetization variable is ignored.
Do not specify both multiplicity and tot_magnetization.
YES, there is redundancy! nelup/neldw are enough to specify
the spin state. However these variables are not very convenient
and will be eliminated from the input in future versions.
It is recommended to use either 'multiplicity' or equivalently
'tot_magnetization' to specify the spin state.
ecfixed REAL
Default: 0.0
See: q2sigma
qcutz REAL
Default: 0.0
See: q2sigma
q2sigma REAL
Default: 0.1
ecfixed, qcutz, q2sigma:  parameters for modified functional to be
used in variable-cell molecular dynamics (or in stress calculation).
"ecfixed" is the value (in Rydberg) of the constant-cutoff;
"qcutz" and "q2sigma" are the height and the width (in Rydberg)
of the energy step for reciprocal vectors whose square modulus
is greater than "ecfixed". In the kinetic energy, G^2 is
replaced by G^2 + qcutz * (1 + erf ( (G^2 - ecfixed)/q2sigma) )
See: M. Bernasconi et al, J. Phys. Chem. Solids 56, 501 (1995)
xc_type CHARACTER
Status: presently UNUSED: XC functional is read from PP files
Exchange-correlation functional
lda_plus_u LOGICAL
Default: .FALSE.
See: Hubbard_U
Hubbard_alpha(i), i=1,ntyp REAL
Default: 0.D0 for all species
See: Hubbard_U
Hubbard_U(i), i=1,ntyp REAL
Default: 0.D0 for all species
Status: LDA+U works only for a few selected elements. Modify PW/set_hubbard_l.f90 and PW/tabd.f90 if you plan to use LDA+U with an element that is not configured there.
lda_plus_u, Hubbard_alpha(i), Hubbard_U(i): parameters for LDA+U
calculations If lda_plus_u = .TRUE. you must specify, for species i,
the parameters U and (optionally) alpha of the Hubbard model (both in eV).
See: Anisimov, Zaanen, and Andersen, PRB 44, 943 (1991); Anisimov
et al., PRB 48, 16929 (1993); Liechtenstein, Anisimov, and Zaanen, PRB
52, R5467 (1994); Cococcioni and de Gironcoli, PRB 71, 035105 (2005).
starting_ns_eigenvalue(m,ispin,I) REAL
Default: -1.d0 that means NOT SET
In the first iteration of an LDA+U run it overwrites
the m-th eigenvalue of the ns occupation matrix for the
ispin component of atomic species I. Leave unchanged
eigenvalues that are not set. This is useful to suggest
the desired orbital occupations when the default choice
takes another path.
U_projection_type CHARACTER
Default: 'atomic'
Only active when lda_plus_U is .true., specifies the type
of projector on localized orbital to be used in the LDA+U
scheme.

Currently available choices:
'atomic': use atomic wfc's (as they are) to build the projector

'ortho-atomic': use Lowdin orthogonalized atomic wfc's

'norm-atomic': Lowdin normalization of atomic wfc. Keep in mind:
atomic wfc are not orthogonalized in this case.
This is a "quick and dirty" trick to be used when
atomic wfc from the pseudopotential are not
normalized (and thus produce occupation whose
value exceeds unity). If orthogonalized wfc are
not needed always try 'atomic' first.

'file': use the information from file "prefix".atwfc that must
have been generated previously, for instance by pmw.x
(see PP/poormanwannier.f90 for details)

NB: forces and stress currently implemented only for the
'atomic' choice.
edir INTEGER
The direction of the electric field or dipole correction is
parallel to the bg(:,edir) reciprocal lattice vector, so the
potential is constant in planes defined by FFT grid points;
edir = 1, 2 or 3. Used only if tefield is .TRUE.
emaxpos REAL
Default: 0.5D0
Position of the maximum of the sawlike potential along crystal
axis "edir", within the unit cell (see below), 0 < emaxpos < 1
Used only if tefield is .TRUE.
eopreg REAL
Default: 0.1D0
Zone in the unit cell where the sawlike potential decreases.
( see below, 0 < eopreg < 1 ). Used only if tefield is .TRUE.
eamp REAL
Default: 0.001 a.u.
Amplitude of the electric field (in a.u. = 51.44 10^10 V/m )
The sawlike potential increases with slope "eamp" in the
region from (emaxpos+eopreg-1) to (emaxpos), then decreases
to 0 until (emaxpos+eopreg), in units of the crystal
vector "edir". Used only if tefield is .TRUE.
angle1(i), i=1,ntyp REAL
The angle expressed in degrees between the initial
magnetization and the z-axis. For noncollinear calculations
only; index i runs over the atom types.
angle2(i), i=1,ntyp REAL
The angle expressed in degrees between the projection
of the initial magnetization on x-y plane and the x-axis.
For noncollinear calculations only.
constrained_magnetization CHARACTER
Default: 'none'
Used to perform constrained calculations in magnetic systems.
Currently available choices:

'none':
no constraint

'total':
total magnetization is constrained
If nspin=4 (noncolin=.True.) constraint is imposed by
adding a penalty functional to the total energy:

LAMBDA * SUM_{i} ( magnetization(i) - fixed_magnetization(i) )**2

where the sum over i runs over the three components of
the magnetization. Lambda is a real number (see below).
If nspin=2 constraint is imposed by defining two Fermi
energies for spin up and down.
Only fixed_magnetization(3) can be defined in this case.

'atomic':
atomic magnetization are constrained to the defined
starting magnetization adding a penalty:

LAMBDA * SUM_{i,itype} ( magnetic_moment(i,itype) - mcons(i,itype) )**2

where i runs over the cartesian components (or just z
in the collinear case) and itype over the types (1-ntype).
mcons(:,:) array is defined from starting_magnetization,
(and angle1, angle2 in the non-collinear case). lambda is
a real number

'total direction':
the angle theta of the total magnetization
with the z axis (theta = fixed_magnetization(3))
is constrained:

LAMBDA * ( magnetization(1) - magnetization(3)*tan(theta) )**2

'atomic direction':
not all the components of the atomic
magnetic moment are constrained but only the cosine
of angle1, and the penalty functional is:

LAMBDA * SUM_{itype} ( mag_mom(3,itype)/mag_mom_tot - cos(angle1(ityp)) )**2
fixed_magnetization(i), i=1,3 REAL
Default: 0.d0
value of the total magnetization to be maintained fixed when
constrained_magnetization='total'
B_field(i), i=1,3 REAL
Default: 0.d0
A fixed magnetic field defined by the vector B_field is added
to the exchange and correlation magnetic field.
The three components of the magnetic field are given in Ry.
Only B_field(3) can be used if nspin=2.

In all calculations with a finite magnetic field,
we print the total energy WITHOUT the B dot M term.
In the calculations with the penalty functional we write
only the total energy, NOT the penalty functional.
lambda REAL
parameter used for constrained_magnetization calculations
NB: LAMBDA is reduced in the first iterations and is increased
slowly up to the input value.
report INTEGER
It's the number of iterations after which the program
write all the atomic magnetic moments.
lspinorb LOGICAL
if .TRUE. the noncollinear code can use a pseudopotential with
spin-orbit.
assume_isolated LOGICAL
Default: .FALSE.
if .TRUE. the system is assumed to be isolated (a molecule or cluster
in a supercell) and the Makov-Payne correction to the total energy is
computed. An estimate of the vacuum level is also calculated so that
eigenvalues can be properly aligned.

Namelist: ELECTRONS

electron_maxstep INTEGER
Default: 100
maximum number of iterations in a scf step
conv_thr REAL
Default: 1.D-6
Convergence threshold for selfconsistency:
estimated energy error < conv_thr
mixing_mode CHARACTER
Default: 'plain'
'plain' :    charge density Broyden mixing

'TF' : as above, with simple Thomas-Fermi screening
(for highly homogeneous systems)

'local-TF': as above, with local-density-dependent TF screening
(for highly inhomogeneous systems)
mixing_beta REAL
Default: 0.7D0
mixing factor for self-consistency
mixing_ndim INTEGER
Default: 8
number of iterations used in mixing scheme
mixing_fixed_ns INTEGER
Default: 0
For LDA+U : number of iterations with fixed ns ( ns is the
atomic density appearing in the Hubbard term ).
diagonalization CHARACTER
Default: 'david'
'david':  Davidson iterative diagonalization with overlap matrix
(default). Fast, may in some rare cases fail.

'cg' : conjugate-gradient-like band-by-band diagonalization
Typically slower than 'david' but it uses less memory
and is more robust (it fails very seldom)

'david-serial': do not use parallel subspace diagonalization
in Davidson algorithm (for testing purposes).
The subspace diagonalization in Davidson is performed
by a fully distributed-memory parallel algorithm on
4 or more processors, by default. The allocated memory
scales down with the number of procs. Procs involved
in diagonalization can be changed with input parameter
"ortho_para". On multicore CPUs often it is convenient
to let only one core per CPU to work on linear algebra.
ortho_para INTEGER
Default: 0
Status: OBSOLESCENT: use command-line option " -ndiag XX" instead
meaningful for diagonalization='david' and parallel executables.
The number of processors to be used for the parallel subspace
diagonalization algorithm. With the default value (0) the code
tries to use as many processors as available. Note that the
algorithm uses a square number of processors (4, 9, 16, 25,...),
so the actual number of processors used will be the largest
square number less or equal to ortho_para (if set) or to the
total number of processors (if ortho_para is not set).
diago_thr_init REAL
Convergence threshold for the first iterative diagonalization
(the check is on eigenvalue convergence).
For scf calculations, the default is 1.D-2 if starting from a
superposition of atomic orbitals; 1.D-5 if starting from a
charge density. During self consistency the threshold (ethr)
is automatically reduced when approaching convergence.
For non-scf calculations, this is the threshold used in the
iterative diagonalization. The default is conv_thr / nelec.
For 'phonon' calculations, diago_thr_init is ignored:
the threshold is always set to conv_thr / nelec .
diago_cg_maxiter INTEGER
For conjugate gradient diagonalization:
max number of iterations
diago_david_ndim INTEGER
Default: 4
For Davidson diagonalization: dimension of workspace
(number of wavefunction packets, at least 2 needed).
A larger value may yield a faster algorithm but uses
more memory
diago_full_acc LOGICAL
Default: .FALSE.
If .TRUE. all the empty states are diagonalized at the same level
of accuracy of the occupied ones. Otherwise the empty states are
diagonalized using a larger threshold (this should not affect
total energy, forces, and other ground-state properties).
efield REAL
Default: 0.D0
For finite electric field calculations (lelfield == .TRUE.),
it defines the intensity of the field in a.u.
startingpot CHARACTER
'atomic': starting potential from atomic charge superposition
( default for scf, *relax, *md, neb, smd )

'file' : start from existing "charge-density.xml" file
( default, only possibility for nscf, bands, phonon )
startingwfc CHARACTER
Default: 'atomic'
'atomic': start from superposition of atomic orbitals
If not enough atomic orbitals are available,
fill with random numbers the remaining wfcs
The scf typically starts better with this option,
but in some high-symmetry cases one can "loose"
valence states, ending up in the wrong ground state.

'atomic+random': as above, plus a superimposed "randomization"
of atomic orbitals. Prevents the "loss" of states
mentioned above.

'random': start from random wfcs. Slower start of scf but safe.
It may also reduce memory usage in conjunction with
diagonalization='cg'

'file': start from a wavefunction file
tqr LOGICAL
Default: .FALSE.
If .true., use the (VERY EXPERIMENTAL) real-space algorithm
for augmentation charges in ultrasoft pseudopotentials.
Must faster execution of ultrasoft-related calculations,
but numerically less accurate than the default algorithm.
Use with care and after testing!

Namelist: IONS

input this namelist only if calculation = 'relax', 'md', 'vc-relax', 'vc-md', 'neb', 'smd'
ion_dynamics CHARACTER
Specify the type of ionic dynamics.

For constrained dynamics or constrained optimisations add the
CONSTRAINTS card (when the card is present the SHAKE algorithm is
automatically used).

For different type of calculation different possibilities are
allowed and different default values apply:

CASE ( calculation = 'relax' )
'bfgs' : (default) a new BFGS quasi-newton algorithm, based
on the trust radius procedure, is used
for structural relaxation (experimental)
'damp' : use damped (quick-min Verlet)
dynamics for structural relaxation

CASE ( calculation = 'md' )
'verlet' : (default) use Verlet algorithm to integrate
Newton's equation
'langevin' ion dynamics is over-damped Langevin

CASE ( calculation = 'vc-relax' )
'damp' : (default) use damped (Beeman) dynamics for
structural relaxation

CASE ( calculation = 'vc-md' )
'beeman' : (default) use Beeman algorithm to integrate
Newton's equation
phase_space CHARACTER
Default: 'full'
'full' :           the full phase-space is used for the ionic
dynamics.

'coarse-grained' : a coarse-grained phase-space, defined by a set
of constraints, is used for the ionic dynamics
(used for calculation of free-energy barriers)
pot_extrapolation CHARACTER
Default: 'atomic'
Used to extrapolate the potential from preceding ionic steps.

'none' : no extrapolation

'atomic' : extrapolate the potential as if it was a sum of
atomic-like orbitals

'first_order' : extrapolate the potential with first-order
formula

'second_order': as above, with second order formula
wfc_extrapolation CHARACTER
Default: 'none'
 Used to extrapolate the wavefunctions from preceding ionic steps.

'none' : no extrapolation

'first_order' : extrapolate the wave-functions with first-order
formula - NOT IMPLEMENTED WITH USPP

'second_order': as above, with second order formula
NOT IMPLEMENTED WITH USPP
remove_rigid_rot LOGICAL
Default: .FALSE.
This keyword is useful when simulating the dynamics and/or the
thermodynamics of an isolated system. If set to true the total
torque of the internal forces is set to zero by adding new forces
that compensate the spurious interaction with the periodic
images. This allowes for the use of smaller supercells.

BEWARE: since the potential energy is no longer consistent with
the forces (it still contains the spurious interaction with the
repeated images), the total energy is not conserved anymore.
However the dynamical and thermodynamical properties should be
in closer agreement with those of an isolated system.
Also the final energy of a structural relaxation will be higher,
but the relaxation itself should be faster.
keywords used for molecular dynamics
ion_temperature CHARACTER
Default: 'not_controlled'
'rescaling'   control ionic temperature via velocity rescaling
(first method) see parameters "tempw" and "tolp"
This is the only method implemented in VC-MD

'rescale-v' control ionic temperature via velocity rescaling
(second method) see parameters "tempw" and "nraise"

'rescale-T' control ionic temperature via velocity rescaling
(third method) see parameter "delta_t"

'reduce-T' reduce ionic temperature every "nraise" steps
by the (negative) value "delta_t"

'berendsen' control ionic temperature using "soft" velocity
rescaling - see parameters "tempw" and "nraise"

'andersen' control ionic temperature using Andersen thermostat
see parameters "tempw" and "nraise"

'not_controlled' (default) ionic temperature is not controlled
tempw REAL
Default: 300.D0
Starting temperature (Kelvin) in MD runs
target temperature for most thermostats.
tolp REAL
Default: 100.D0
Tolerance for velocity rescaling. Velocities are rescaled if
the run-averaged and target temperature differ more than tolp.
delta_t REAL
Default: 1.D0
if ion_temperature='rescale-T':
at each step the instantaneous temperature is multiplied
by delta_t; this is done rescaling all the velocities.

if ion_temperature='reduce-T':
every 'nraise' steps the instantaneous temperature is
reduced by -delta_T (.e. delta_t is added to the temperature)

The instantaneous temperature is calculated at the end of
every ionic move and BEFORE rescaling. This is the temperature
reported in the main output.

For delta_t < 0, the actual average rate of heating or cooling
should be roughly C*delta_t/(nraise*dt) (C=1 for an
ideal gas, C=0.5 for a harmonic solid, theorem of energy
equipartition between all quadratic degrees of freedom).
nraise INTEGER
Default: 1
if ion_temperature='reduce-T':
every 'nraise' steps the instantaneous temperature is
reduced by -delta_T (.e. delta_t is added to the temperature)

if ion_temperature='rescale-v':
every 'nraise' steps the average temperature, computed from
the last nraise steps, is rescaled to tempw

if ion_temperature='berendsen':
the "rise time" parameter is given in units of the time step:
tau = nraise*dt, so dt/tau = 1/nraise

if ion_temperature='andersen':
the "collision frequency" parameter is given as nu=1/tau
defined above, so nu*dt = 1/nraise
refold_pos LOGICAL
Default: .FALSE.
This keyword applies only in the case of molecular dynamics or
damped dynamics. If true the ions are refolded at each step into
the supercell.
keywords used only in BFGS calculations
upscale REAL
Default: 10.D0
Max reduction factor for conv_thr during structural optimization
conv_thr is automatically reduced when the relaxation
approaches convergence so that forces are still accurate,
but conv_thr will not be reduced to less that
conv_thr / upscale.
bfgs_ndim INTEGER
Default: 1
Number of old forces and displacements vectors used in the
PULAY mixing of the residual vectors obtained on the basis
of the inverse hessian matrix given by the BFGS algorithm.
When bfgs_ndim = 1, the standard quasi-Newton BFGS method is
used.
(bfgs only)
trust_radius_max REAL
Default: 0.8D0
Maximum ionic displacement in the structural relaxation.
(bfgs only)
trust_radius_min REAL
Default: 1.D-3
Minimum ionic displacement in the structural relaxation
BFGS is reset when trust_radius < trust_radius_min.
(bfgs only)
trust_radius_ini REAL
Default: 0.5D0
Initial ionic displacement in the structural relaxation.
(bfgs only)
w_1 REAL
Default: 0.01D0
See: w_2
w_2 REAL
Default: 0.5D0
Parameters used in line search based on the Wolfe conditions.
(bfgs only)
keywords used only in NEB and SMD calculations
num_of_images INTEGER
Default: 0
Number of points used to discretize the path
(it must be larger than 3).
opt_scheme CHARACTER
Default: 'quick-min'
Specify the type of optimization scheme:

'sd' : steepest descent

'broyden' : quasi-Newton Broyden's second method (suggested)

'quick-min' : an optimisation algorithm based on the
projected velovity Verlet scheme

'langevin' : finite temperature langevin dynamics of the
string (smd only). It is used to compute the
average path and the free-energy profile.
CI_scheme CHARACTER
Default: 'no-CI'
Specify the type of Climbing Image scheme:

'no-CI' : climbing image is not used

'auto' : original CI scheme. The image highest in energy
does not feel the effect of springs and is
allowed to climb along the path

'manual' : images that have to climb are manually selected.
See also CLIMBING_IMAGES card
first_last_opt LOGICAL
Default: .FALSE.
Also the first and the last configurations are optimised
"on the fly" (these images do not feel the effect of the springs).
temp_req REAL
Default: 0.D0 Kelvin
Temperature used for the langevin dynamics of the string.
ds REAL
Default: 1.D0
Optimisation step length ( Hartree atomic units ).
If opt_scheme="broyden", ds is used as a guess for the diagonal
part of the Jacobian matrix.
k_max, k_min REAL
Default: 0.1D0 Hartree atomic units
Set them to use a Variable Elastic Constants scheme
elastic constants are in the range [ k_min, k_max ]
this is useful to rise the resolution around the saddle point.
path_thr REAL
Default: 0.05D0 eV / Angstrom
The simulation stops when the error ( the norm of the force
orthogonal to the path in eV/A ) is less than path_thr.
use_masses LOGICAL
Default: .FALSE.
If. TRUE. the optimisation of the path is performed using
mass-weighted coordinates.
use_freezing LOGICAL
Default: .FALSE.
If. TRUE. the images are optimised according to their error:
only those images with an error larger than half of the largest
are optimised. The other images are kept frozen.
keywords used only in meta-dynamics calculations ( see also the card COLLECTIVE_VARS )
fe_step(i), i=1,ncolvar REAL
Default: 0.04
Meta-dynamics step length (in principle different for each
collective variable), defined using the same units used
to define the collective variables themselves.
The step also defines the spread of the Gaussian-like bias
potential.
g_amplitude REAL
Default: 0.005 Hartree
Amplitude of the gaussians used in meta-dynamics.
fe_nstep INTEGER
Default: 100
Maximum number of steps used to evaluate the potential of
mean force.
sw_nstep INTEGER
Default: 10
Number of steps used to switch to the new values of the
collective variables.

Namelist: CELL

input this namelist only if calculation = 'vc-relax', 'vc-md'
cell_dynamics CHARACTER
Specify the type of dynamics for the cell.
For different type of calculation different possibilities
are allowed and different default values apply:

CASE ( calculation = 'vc-relax' )
'none': default
'sd': steepest descent ( not implemented )
'damp-pr': damped (Beeman) dynamics of the Parrinello-Rahman
extended lagrangian
'damp-w': damped (Beeman) dynamics of the new Wentzcovitch
extended lagrangian
'bfgs': new BFGS quasi-newton algorithm, based on the trust
radius procedure, is used for structural relaxation
(experimental), ion_dynamics must be 'bfgs' too
CASE ( calculation = 'vc-md' )
'none': default
'pr': (Beeman) molecular dynamics of the Parrinello-Rahman
extended lagrangian
'w': (Beeman) molecular dynamics of the new Wentzcovitch
extended lagrangian
press REAL
Default: 0.D0
Target pressure [KBar] in a variable-cell md or relaxation run.
wmass REAL
Default: 0.75*Tot_Mass/pi**2 for Parrinello-Rahman MD; 0.75*Tot_Mass/pi**2/Omega**(2/3) for Wentzcovitch MD
Fictitious cell mass [amu] for variable-cell simulations
(both 'vc-md' and 'vc-relax')
cell_factor REAL
Default: 1.2D0
Used in the construction of the pseudopotential tables.
It should exceed the maximum linear contraction of the
cell during a simulation.
press_conv_thr REAL
Default: 0.5D0 Kbar
Convergence threshold on the pressure for variable cell
relaxation ('vc-relax' : note that the other convergence
thresholds for ionic relaxation apply as well).
cell_dofree CHARACTER
Default: 'all'
Select which of the cell parameters should be moved:

all = all axis and angles are propagated
volume = the cell is simply rescaled, without changing the shape
x = only the x axis is moved
y = only the y axis is moved
z = only the z axis is moved
xy = only the x and y axis are moved, angles are unchanged
xz = only the x and z axis are moved, angles are unchanged
yz = only the y and z axis are moved, angles are unchanged
xyz = x, y and z axis are moved, angles are unchanged
xyt = x1, x2, y2 (i.e. lower xy triangle of the 2 vectors)
xys = x1, y1, x2, y2 (i.e. xy square of the 2 vectors)
xyzt = x1, x2, y2, x3, y3, z3 (i.e. lower xyz triangle of
the 3 vectors)

Namelist: PHONON

input this namelist only in calculation = 'phonon'
modenum INTEGER
Default: 0
For single-mode phonon calculation : modenum is the index of the
irreducible representation (irrep) into which the reducible
representation formed by the 3*nat atomic displacements are
decomposed in order to perform the phonon calculation.
xqq(i), i=1,3 REAL
q-point (units 2pi/a) for phonon calculation.

Card: ATOMIC_SPECIES

Syntax:

ATOMIC_SPECIES
 X(1)   Mass_X(1)   PseudoPot_X(1) 
 X(2)   Mass_X(2)   PseudoPot_X(2) 
 . . .
 X(ntyp)   Mass_X(ntyp)   PseudoPot_X(ntyp) 

Description of items:

X CHARACTER
 label of the atom
Mass_X REAL
mass of the atomic species [amu: mass of C = 12]
not used if calculation='scf','nscf', 'bands', 'phonon'
PseudoPot_X CHARACTER
File containing PP for this species.

The pseudopotential file is assumed to be in the new UPF format.
If it doesn't work, the pseudopotential format is determined by
the file name:

*.vdb or *.van Vanderbilt US pseudopotential code
*.RRKJ3 Andrea Dal Corso's code (old format)
none of the above old PWscf norm-conserving format

Card: ATOMIC_POSITIONS { alat | bohr | angstrom | crystal }

IF calculation != 'neb' AND calculation != 'smd' :

Syntax:

ATOMIC_POSITIONS { alat | bohr | angstrom | crystal }
 X(1)   x(1)   y(1)   z(1)  {  if_pos(1)(1)   if_pos(2)(1)   if_pos(3)(1)  }
 X(2)   x(2)   y(2)   z(2)  {  if_pos(1)(2)   if_pos(2)(2)   if_pos(3)(2)  }
 . . .
 X(nat)   x(nat)   y(nat)   z(nat)  {  if_pos(1)(nat)   if_pos(2)(nat)   if_pos(3)(nat)  }
ELSEIF calculation = 'neb' OR calculation = 'smd' :
There are at least two groups of cards, each group is composed
by an identifier followed by "nat" lines as specified above:

identifier
X x y z { if_pos(1) if_pos(2) if_pos(3) }

The first group ( identifier="first_image" ) contains the first image;
the last group ( identifier="last_image" ) contains the last image.

There is also the possibility of specifying intermediate images;
in this case their coordinates must be set between the first_image
and the last_image ( identifier="intermediate_image", followed by
"nat" position lines ).

IMPORTANT:
Several intermediate images may be specified via intermediate_image
identifier, but the total number of configurations specified in the
input file must be less than num_of_images (as specified in &IONS).
The initial path is obtained interpolating between the specified
configurations so that all images are equispaced (only the coordinates
of the first and last images are not changed).

Syntax:

ATOMIC_POSITIONS { alat | bohr | angstrom | crystal }
first_image  
 X(1)    x(1)    y(1)    z(1)   {  if_pos(1)(1)    if_pos(2)(1)    if_pos(3)(1)   }
 X(2)    x(2)    y(2)    z(2)   {  if_pos(1)(2)    if_pos(2)(2)    if_pos(3)(2)   }
 . . .
 X(nat)    x(nat)    y(nat)    z(nat)   {  if_pos(1)(nat)    if_pos(2)(nat)    if_pos(3)(nat)   }
{ intermediate_image  
 X(1)    x(1)    y(1)    z(1)  
 X(2)    x(2)    y(2)    z(2)  
 . . .
 X(nat)    x(nat)    y(nat)    z(nat)  
} last_image  
 X(1)    x(1)    y(1)    z(1)  
 X(2)    x(2)    y(2)    z(2)  
 . . .
 X(nat)    x(nat)    y(nat)    z(nat)  

Description of items:

alat    : atomic positions are in cartesian coordinates,
in units of the lattice parameter "a" (default)

bohr : atomic positions are in cartesian coordinate,
in atomic units (i.e. Bohr)

angstrom: atomic positions are in cartesian coordinates,
in Angstrom

crystal : atomic positions are in crystal coordinates, i.e.
in relative coordinates of the primitive lattice vectors (see below)
X CHARACTER
 label of the atom as specified in ATOMIC_SPECIES
x, y, z REAL
 atomic positions
if_pos(1), if_pos(2), if_pos(3) INTEGER
Default: 1
component i of the force for this atom is multiplied by if_pos(i),
which must be either 0 or 1. Used to keep selected atoms and/or
selected components fixed in meta-dynamics, neb, smd, MD dynamics or
structural optimization run.

Card: K_POINTS { tpiba | automatic | crystal | gamma }

IF tpiba OR crystal :

Syntax:

K_POINTS tpiba | crystal
nks  
 xk_x(1)   xk_y(1)   xk_z(1)   wk(1) 
 xk_x(2)   xk_y(2)   xk_z(2)   wk(2) 
 . . .
 xk_x(nks)   xk_y(nks)   xk_z(nks)   wk(nks) 
ELSEIF automatic :

Syntax:

K_POINTS automatic
nk1  nk2  nk3  sk1  sk2  sk3  
ELSEIF gamma :

Syntax:

K_POINTS gamma

Description of items:

tpiba    : read k-points in cartesian coordinates,
in units of 2 pi/a (default)

automatic: automatically generated uniform grid of k-points, i.e,
generates ( nk1, nk2, nk3 ) grid with ( sk1, sk2, sk3 ) offset.
nk1, nk2, nk3 as in Monkhorst-Pack grids
k1, k2, k3 must be 0 ( no offset ) or 1 ( grid displaced
by half a grid step in the corresponding direction )
BEWARE: only grids having the full symmetry of the crystal
work with tetrahedra. Some grids with offset may not work.

crystal : read k-points in crystal coordinates, i.e. in relative
coordinates of the reciprocal lattive vectors

gamma : use k = 0 (no need to list k-point specifications after card)
In this case wavefunctions can be chosen as real,
and specialized subroutines optimized for calculations
at the gamma point are used (memory and cpu requirements
are reduced by approximately one half).
nks INTEGER
 Number of supplied special k-points.
xk_x, xk_y, xk_z, wk REAL
Special k-points (xk_x/y/z) in the irreducible Brillouin Zone
of the lattice (with all symmetries) and weights (wk)
See the literature for lists of special points and
the corresponding weights.

If the symmetry is lower than the full symmetry
of the lattice, additional points with appropriate
weights are generated.

In a non-scf calculation, weights do not affect the results.
If you just need eigenvalues and eigenvectors (for instance,
for a band-structure plot), weights can be set to any value
(for instance all equal to 1).
nk1, nk2, nk3 INTEGER
These parameters specify the k-point grid
(nk1 x nk2 x nk3) as in Monkhorst-Pack grids.
sk1, sk2, sk3 INTEGER
The grid offests;  sk1, sk2, sk3 must be
0 ( no offset ) or 1 ( grid displaced by
half a grid step in the corresponding direction ).

Card: CELL_PARAMETERS { cubic | hexagonal }

Optional card, needed only if ibrav = 0 is specified, ignored otherwise !

Syntax:

CELL_PARAMETERS { cubic | hexagonal }

 v1(1)   v1(2)   v1(3) 

 v2(1)   v2(2)   v2(3) 

 v3(1)   v3(2)   v3(3) 

Description of items:

Flag "cubic" or "hexagonal" specify if you want to look for symmetries
derived from the cubic symmetry group (default) or from the hexagonal
symmetry group (assuming c axis as the z axis, a axis along the x axis).
v1, v2, v3 REAL
Crystal lattice vectors:
v1(1) v1(2) v1(3) ... 1st lattice vector
v2(1) v2(2) v2(3) ... 2nd lattice vector
v3(1) v3(2) v3(3) ... 3rd lattice vector

In alat units if celldm(1) was specified or in a.u. otherwise.

Card: CLIMBING_IMAGES

Optional card, needed only if CI_scheme = 'manual', ignored otherwise !

Syntax:

CLIMBING_IMAGES
index1, index2, ... indexN   

Description of items:

index1, index2, ... indexN INTEGER
index1, index2, ..., indexN are indices of the images to which the
Climbing-Image procedure apply. If more than one image is specified
they must be separated by a comma.

Card: CONSTRAINTS

Optional card, used for constrained dynamics or constrained optimisations !
When this card is present the SHAKE algorithm is automatically used.

Syntax:

CONSTRAINTS
nconstr   { constr_tol   }
 constr_type(1)   constr(1)(1)   constr(2)(1)  [  constr(3)(1)    constr(4)(1)   ] {  constr_target(1)  }
 constr_type(2)   constr(1)(2)   constr(2)(2)  [  constr(3)(2)    constr(4)(2)   ] {  constr_target(2)  }
 . . .
 constr_type(nconstr)   constr(1)(nconstr)   constr(2)(nconstr)  [  constr(3)(nconstr)    constr(4)(nconstr)   ] {  constr_target(nconstr)  }

Description of items:

nconstr INTEGER
 Number of constraints.
constr_tol REAL
 Tolerance for keeping the constraints satisfied.
constr_type CHARACTER
Type of constrain :

'type_coord' : constraint on global coordination-number, i.e. the
average number of atoms of type B surrounding the
atoms of type A. The coordination is defined by
using a Fermi-Dirac.
(four indexes must be specified).

'atom_coord' : constraint on local coordination-number, i.e. the
average number of atoms of type A surrounding a
specific atom. The coordination is defined by
using a Fermi-Dirac.
(four indexes must be specified).

'distance' : constraint on interatomic distance
(two atom indexes must be specified).

'planar_angle' : constraint on planar angle
(three atom indexes must be specified).

'torsional_angle' : constraint on torsional angle
(four atom indexes must be specified).

'bennett_proj' : constraint on the projection onto a given direction
of the vector defined by the position of one atom
minus the center of mass of the others.
( Ch.H. Bennett in Diffusion in Solids, Recent
Developments, Ed. by A.S. Nowick and J.J. Burton,
New York 1975 ).
constr(1), constr(2), constr(3), constr(4)
                      These variables have different meanings
for different constraint types:

'type_coord' : constr(1) is the first index of the
atomic type involved
constr(2) is the second index of the
atomic type involved
constr(3) is the cut-off radius for
estimating the coordination
constr(4) is a smoothing parameter

'atom_coord' : constr(1) is the atom index of the
atom with constrained coordination
constr(2) is the index of the atomic
type involved in the coordination
constr(3) is the cut-off radius for
estimating the coordination
constr(4) is a smoothing parameter

'distance' : atoms indices object of the
constraint, as they appear in
the 'ATOMIC_POSITION' CARD

'planar_angle', 'torsional_angle' : atoms indices object of the
constraint, as they appear in the
'ATOMIC_POSITION' CARD (beware the
order)

'bennett_proj' : constr(1) is the index of the atom
whose position is constrained.
constr(2:4) are the three coordinates
of the vector that specifies the
constraint direction.
constr_target REAL
Target for the constrain ( angles are specified in degrees ).
This variable is optional.

Card: COLLECTIVE_VARS

Optional card, used for meta-dynamics calculations !

Syntax:

COLLECTIVE_VARS
ncolvar   { colvar_tol   }
 colvar_type(1)   colvar(1)(1)   colvar(2)(1)  [  colvar(3)(1)    colvar(4)(1)   ]
 colvar_type(2)   colvar(1)(2)   colvar(2)(2)  [  colvar(3)(2)    colvar(4)(2)   ]
 . . .
 colvar_type(ncolvar)   colvar(1)(ncolvar)   colvar(2)(ncolvar)  [  colvar(3)(ncolvar)    colvar(4)(ncolvar)   ]

Description of items:

ncolvar INTEGER
 Number of collective variables.
colvar_tol REAL
 Tolerance used for SHAKE.
colvar_type CHARACTER
See: constr_type
See the definition of constr_type in the CONSTRAINTS card.
colvar(1), colvar(2), colvar(3), colvar(4)
See: constr(1)
These variables have different meanings for
different collective variable types. See the
definition of constr in the CONSTRAINTS card.

Card: OCCUPATIONS

Optional card, used only if occupations = 'from_input', ignored otherwise !

Syntax:

OCCUPATIONS

 f_inp1(1)   f_inp1(2)   . . .  f_inp1(nbnd) 
[    f_inp2(1)   f_inp2(2)   . . .  f_inp2(nbnd)    ]

Description of items:

f_inp1 REAL
Occupations of individual states.
For spin-polarized calculation, these are majority spin states.
f_inp2 REAL
Occupations of minority spin states for spin-polarized calculation;
specify only for spin-polarized calculation.
This file has been created by helpdoc utility.
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