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*{{TAG|INCAR}}
{{Template:At_and_mol - Tutorial}}
 
== Task ==
 
Relaxation of the bond length in a CO molecule.
 
== Input ==
 
=== {{TAG|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
 
=== {{TAG|INCAR}} ===
  {{TAGBL|SYSTEM}} = CO molecule in a box
  {{TAGBL|SYSTEM}} = CO molecule in a box
  {{TAGBL|ISMEAR}} = 0 ! Gaussian smearing
  {{TAGBL|ISMEAR}} = 0 ! Gaussian smearing
Line 5: Line 24:
  {{TAGBL|IBRION}} = 2 ! use the conjugate gradient algorithm
  {{TAGBL|IBRION}} = 2 ! use the conjugate gradient algorithm


*{{TAG|KPOINTS}}
=== {{TAG|KPOINTS}} ===
  Gamma-point only
  Gamma-point only
   0
   0
Line 12: Line 31:
   0 0 0
   0 0 0


*{{TAG|POSCAR}}
=== {{TAG|POTCAR}} ===
  CO molecule in a box
 
  1.0          ! universal scaling parameters
The {{TAG|POTCAR}} file is created by the concatenation of two individual {{TAG|POTCAR}} files corresponding to O and C, e.g.:
   8.0 0.0 0.0 ! lattice vector  a(1)
  cat  .../O/POTCAR  .../C POTCAR  > POTCAR
   0.0 8.0 0.0  ! lattice vector a(2)
 
   0.0 0.0 8.0  ! lattice vector  a(3)
== Calculation ==
  1 1          ! number of atoms for each species
 
  cart          ! positions in cartesian coordinates
*A similar relaxation as in the previous case ({{TAG|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 ({{TAG|POTIM}} parameter).
   0 0 0       ! first atom
 
   0 0 1.12    ! second atom
    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 ==
== Download ==
[http://www.vasp.at/vasp-workshop/examples/CO.tgz CO.tgz]
[[Media:CO.tgz| CO.tgz]]
----
[[VASP_example_calculations|To the list of examples]] or to the [[The_VASP_Manual|main page]]
{{Template:At_and_mol}}


[[Category:Examples]]
[[Category:Examples]]

Latest revision as of 13:18, 14 November 2019

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