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By using a carbon monoxide (CO) in a small rectangular box as an example, short description on the input variables is provided here.
nfinp_scf
:
WF_OPT DAV NTYP 2 NATM 2 GMAX 5.50 GMAXP 20.00 NSCF 200 MIX_ALPHA 0.8 WIDTH 0.0010 EDELTA 0.1000D-09 NEG 8 CELL 6.00 4.00 4.00 90.00 90.00 90.00 &ATOMIC_SPECIES C 12.011 pot.C_pbe1 O 15.999 pot.O_pbe1 &END &ATOMIC_COORDINATES 0.0000 0.0000 0.0000 1 1 1 2.2000 0.0000 0.0000 1 1 2 &END
Each input variables and blocks (&[BLOCK_NAME] ... &) are explained below:
WF_OPT DAV
WF_OPT
is used to specify the wave function method. Default is DAV
.
NTYP 2
NTYP
defines the number of atomic species in the system.
NATM 2
NATM
defines the number of atoms in the unit cell.
GMAX 5.50
GMAX
is the cutoff wave vector for the plane wave expansion of the wave functions. GMAX**2 corresponds to the cutoff energy in Rydberg.
GMAXP 20.00
GMAXP
is the cutoff wave vector for the plane wave expansion of charge density. GMAXP**2 corresponds to the cutoff energy in Rydberg.
NSCF 200
NSCF
is the maximum number of iteration for the wave function optimization [self-consistent field (SCF)]. Default is 200.
MIX_ALPHA 0.8
MIX_ALPHA
is the mixing parameter for the charge density mixing. Default is 0.7.
WIDTH 0.0010
WIDTH
is the width of the broadening to approximate the delta function in Hartree. For systems with a gap, very small positive WIDTH
is used. In such a case, it does not have a physical meaning and is used to determine the Fermi level.
EDELTA 0.1000D-09
EDELTA
is the convergence threshold for the total energy in Hartree per atom for the SCF calculation.
NEG 8
NEG
is the number of states/bands considered in the calculation. STATE does not allow an occupied-state only calculation, and therefore NEG
should be large enough to include occupied states and some unoccupied states.
CELL 6.00 4.00 4.00 90.00 90.00 90.00
CELL
defines the cell parameter a, b, c, \alpha, \beta, and \gamma, where a, b, c, are the lengths (in Bohr) of the 1st, 2nd, and 3rd lattice vectors, respectively, and \alpha, \beta, and \gamma, are the angles (in degree) between 2nd and 3rd, 3rd and 1st, and 1st and 2nd lattice vectors, respectively.
See below for pictorial description.
&ATOMIC_SPECIES
C 12.011 pot.C_pbe1
O 15.999 pot.O_pbe1
&END
The block &ATOMIC_SPECIES ... &END
is used to define the atomic types. The syntax is similar to the one in Quantum-ESPRESSO.
Syntax:
&ATOMIC_SPECIES ATOMIC_NUMBER(1) ATOMIC_MASS(1) PSEUDOPOTENTIAL_FILE(1) ATOMIC_NUMBER(2) ATOMIC_MASS(2) PSEUDOPOTENTIAL_FILE(2) ... ATOMIC_NUMBER(NTYP) ATOMIC_MASS(NTYP) PSEUDOPOTENTIAL_FILE(NTYP) &ENDor:
&ATOMIC_SPECIES ATOMIC_SYMBOL(1) ATOMIC_MASS(1) PSEUDOPOTENTIAL_FILE(1) ATOMIC_SYMBOL(2) ATOMIC_MASS(2) PSEUDOPOTENTIAL_FILE(2) ... ATOMIC_SYMBOL(NTYP) ATOMIC_MASS(NTYP) PSEUDOPOTENTIAL_FILE(NTYP) &ENDwhere
NTYP
is the number of atomic species.
&ATOMIC_COORDINATES
0.0000 0.0000 0.0000 1 1 1
2.2000 0.0000 0.0000 1 1 2
&END
The block &ATOMIC_COORDINATES ... &END
is used to define the atomic coordinates in the legacy STATE format.
Syntax:
&ATOMIC_COORDINATES [CRYSTAL|CRYS|CARTESIAN|CART] CPS(1,1) CPS(1,2) CPS(1,3) IWEI(1) IMDTYP(1) ITYP(1) CPS(2,1) CPS(2,2) CPS(2,3) IWEI(2) IMDTYP(2) ITYP(2) ... CPS(NATM,1) CPS(NATM,2) CPS(NATM,3) IWEI(NATM) IMDTYP(NATM) ITYP(NATM) &END
CARTESIAN
/CART
: If set, atomic coordinates are given in the cartesian coordinate
CRYSTAL
/CRYS
: If set, atomic coordinates are given in the crystal coordinate
CPS
: Atomic coordinate in the cartesian (NCORD=1
orCOORD=CARTESIAN
) or in the crystal (NCORD=0
orCOORD=CRYSTAL
) coordinate
IWEI
: number of equivalent atoms under the inversion symmetry (currently inversion symmetry is disabled and alwaysIWEI
is always set to 1).
IMDTYP
:
- 1: Allow to move the ion
- 0: Fix the ion
Default coordinate system is
CARTESIAN
. This is chosen when&ATOMIC_COORDINATES
without argument is used.