O atom

Overview > O atom > O atom spinpolarized > O atom spinpolarized low symmetry > Videotutorial

• POSCAR

O atom in a box
 1.0          ! universal scaling parameters
 8.0 0.0 0.0  ! lattice vector  a(1)
 0.0 8.0 0.0  ! lattice vector  a(2)
 0.0 0.0 8.0  ! lattice vector  a(3)
1             ! number of atoms
cart          ! positions in cartesian coordinates
 0 0 0

We are using a POSCAR file with a single atom. Sufficiently large lattice parameters are selected so that no (significant) interactions between atoms in neighbouring cells is present.

• INCAR

SYSTEM = O atom in a box
ISMEAR = 0  ! Gaussian smearing

• KPOINTS

Gamma-point only
 0
Monkhorst Pack
 1 1 1
 0 0 0

For atoms or molecules a single k point is sufficient. When more k-points are used only the interaction between atoms (which should be zero) is described more accurately.

Example output (stdout) for the O atom (using VASP version 5.4.1):

running on    8 total cores
distrk:  each k-point on    8 cores,    1 groups
distr:  one band on    1 cores,    8 groups
using from now: INCAR     
vasp.5.4.1 05Feb16 (build Aug 22 2016 16:46:23) complex                        
POSCAR found :  1 types and       1 ions
scaLAPACK will be used
LDA part: xc-table for Pade appr. of Perdew
POSCAR, INCAR and KPOINTS ok, starting setup
WARNING: small aliasing (wrap around) errors must be expected
FFT: planning ...
WAVECAR not read
entering main loop
N       E                     dE             d eps       ncg     rms          rms(c)
DAV:   1     0.384469664751E+02    0.38447E+02   -0.96726E+02    16   0.293E+02
DAV:   2     0.345965628955E+01   -0.34987E+02   -0.34942E+02    32   0.450E+01
DAV:   3    -0.244485866931E+00   -0.37041E+01   -0.34307E+01    16   0.308E+01
DAV:   4    -0.312557021227E+00   -0.68071E-01   -0.66914E-01    16   0.508E+00
DAV:   5    -0.313520305300E+00   -0.96328E-03   -0.96311E-03    32   0.506E-01    0.286E-01
DAV:   6    -0.314540466589E+00   -0.10202E-02   -0.17853E-03    16   0.332E-01    0.142E-01
DAV:   7    -0.314637222361E+00   -0.96756E-04   -0.22710E-04    16   0.134E-01
1 F= -.31463722E+00 E0= -.16037490E+00  d E =-.308525E+00
writing wavefunctions 

The initial charge corresponds to the charge of isolated overlapping atoms (POTCAR file). For the first 4 steps the charge remains fixed, then the charge is updated (rms(c) column)

Short explanation of the symbols in the OSZICAR and stdout file:

N	iteration count
E	total energy
dE	change of total energy
d	eps change of the eiegenvalues (fixed potential)
ncg	number of optimisation steps $\mathrm{H} \psi$
rms	total residual vector $\sum_{nk} w_{k} f_{nk} (\mathrm{H} - \epsilon_{nk}) \psi_{nk}$
rms(c)	charge density residual vector

Download

Oatom.tgz

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