CO

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Task

Relaxation of the bond length in a CO molecule.

Input

POSCAR

CO molecule 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 1           ! number of atoms for each species
cart          ! positions in cartesian coordinates
 0 0 0        ! first atom
 0 0 1.12     ! second atom

INCAR

SYSTEM = CO molecule in a box
ISMEAR = 0 ! Gaussian smearing
NSW = 5    ! 5 ionic steps
IBRION = 2 ! use the conjugate gradient algorithm

KPOINTS

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

POTCAR

The POTCAR file is created by the concatenation of two individual POTCAR files corresponding to O and C, e.g.:

cat  .../O/POTCAR  .../C POTCAR  > POTCAR

Calculation

• A similar relaxation as in the previous case (O_dimer) is performed but in this case more steps are required, since the first estimate for the minimum is not very accurate. The trial steps are much too long (POTIM parameter).

   1 F= -.14764064E+02 E0= -.14764064E+02  d E =-.147641E+02
 curvature:   0.00 expect dE= 0.000E+00 dE for cont linesearch  0.000E+00
 trial: gam= 0.00000 g(F)=  0.820E+00 g(S)=  0.000E+00 ort = 0.000E+00 (trialstep = 0.100E+01)
 search vector abs. value=  0.820E+00
 bond charge predicted
...         ...      ...
...         ...      ...
...         ...      ...
   2 F= -.12660858E+02 E0= -.12660858E+02  d E =0.210321E+01
 trial-energy change:    2.103205  1 .order    1.311207   -0.819873    3.442288
 step:   0.1924(harm=  0.1924)  dis= 0.02705  next Energy=   -14.842919 (dE=-0.789E-01)
 bond charge predicted
...         ...      ...
...         ...      ...
...         ...      ...
   3 F= -.14747869E+02 E0= -.14747869E+02  d E =0.161943E-01
 curvature:  -0.10 expect dE=-0.902E-01 dE for cont linesearch -0.902E-01
 ZBRENT: interpolating
 opt :   0.0929  next Energy=   -14.802162 (dE=-0.381E-01)
 bond charge predicted
...         ...      ...
...         ...      ... 
...         ...      ...
   4 F= -.14796822E+02 E0= -.14796822E+02  d E =-.327586E-01
 curvature:  -0.04 expect dE=-0.330E-03 dE for cont linesearch -0.330E-03
 trial: gam= 0.00000 g(F)=  0.814E-02 g(S)= 0.000E+00 ort =-0.817E-01 (trialstep = 0.819E+00)
 search vector abs. value=  0.814E-02
 reached required accuracy - stopping structural energy minimisation

Download

CO.tgz