H2O: Difference between revisions

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(Created page with '*INCAR PREC = Normal ! standard precision ENMAX = 400 ! cutoff should be set manually ISMEAR = 0 ; SIGMA = 0.1 IBRION = 1 ! use DIIS algorithm to converge NFR…')
 
 
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*INCAR
{{Template:At_and_mol - Tutorial}}
PREC = Normal    ! standard precision
ENMAX = 400      ! cutoff should be set manually
ISMEAR = 0 ; SIGMA = 0.1
IBRION = 1      ! use DIIS algorithm to converge
NFREE = 2        ! 2 independent degrees of freedom
NSW = 10        ! 10 ionic steps
EDIFFG = -0.02  ! forces smaller 0.02 A/eV


*KPOINTS
== Task ==
Gamma-point only
 
  1        ! one k-point
Relaxation of an <math>\mathrm{H}_{2}\mathrm{O}</math> molecule.
rec      ! in units of the reciprocal lattice vector
 
  0 0 0 1  ! 3 coordinates and weight
== Input ==


*POSCAR
=== {{TAG|POSCAR}} ===
  H2O _2
  H2O _2
  0.52918  ! scaling parameter
  0.52918  ! scaling parameter
Line 26: Line 19:
       1.10    -1.43    0.00 T T F
       1.10    -1.43    0.00 T T F
       1.10    1.43    0.00 T T F
       1.10    1.43    0.00 T T F
All coordinates are scaled by the factor 0.52918.
=== {{TAG|INCAR}} ===
{{TAGBL|PREC}} = Normal    ! standard precision
{{TAGBL|ENMAX}} = 400      ! cutoff should be set manually
{{TAGBL|ISMEAR}} = 0 ; {{TAGBL|SIGMA}} = 0.1
{{TAGBL|IBRION}} = 1      ! use DIIS algorithm to converge
{{TAGBL|NFREE}} = 2        ! 2 independent degrees of freedom
{{TAGBL|NSW}} = 10        ! 10 ionic steps
{{TAGBL|EDIFFG}} = -0.02  ! forces smaller 0.02 A/eV
=== {{TAG|KPOINTS}} ===
Gamma-point only
  0
Monkhorst Pack
  1 1 1
  0 0 0
== Calculation ==
*Use {{TAG|PREC}}=''Normal'' (Default for VASP.5.X)
*It is strongly urged that the energy cutoffs are set manually in the {{TAG|INCAR}} file, as it provides more control over the calculations.
*For the ionic optimization the DIIS algorithm is used. This algorithm builds an approximation of the Hessian matrix and converges usually faster than the conjugate gradient algorithm. It is however recommended to set the independent degrees of freedom manually. *{{TAG|EDIFFG}} determines when to terminate the relaxation. Positive values: energy change between steps must be less than the value set by {{TAG|EDIFFG}}. Negative values: <math>|\mathbf{F}_{i}| < |\mathrm{EDIFFG}| \forall i=1,N_{\mathrm{ions}} </math>.


== Download ==
== Download ==
[http://www.vasp.at/vasp-workshop/examples/1_7_H2O.tgz 1_7_H2O.tgz]
[[Media:H2O.tgz| H2O.tgz]]
 
----
{{Template:At_and_mol}}
[[VASP_example_calculations|To the list of examples]] or to the [[The_VASP_Manual|main page]]


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

Latest revision as of 13:46, 14 November 2019

Task

Relaxation of an molecule.

Input

POSCAR

H2O _2
0.52918   ! scaling parameter
 15 0 0
 0 15 0
 0 0 15
1 2
select
cart
     0.00     0.00     0.00 F F F
     1.10    -1.43     0.00 T T F
     1.10     1.43     0.00 T T F

All coordinates are scaled by the factor 0.52918.

INCAR

PREC = Normal    ! standard precision 
ENMAX = 400      ! cutoff should be set manually
ISMEAR = 0 ; SIGMA = 0.1
IBRION = 1       ! use DIIS algorithm to converge
NFREE = 2        ! 2 independent degrees of freedom
NSW = 10         ! 10 ionic steps
EDIFFG = -0.02   ! forces smaller 0.02 A/eV

KPOINTS

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

Calculation

  • Use PREC=Normal (Default for VASP.5.X)
  • It is strongly urged that the energy cutoffs are set manually in the INCAR file, as it provides more control over the calculations.
  • For the ionic optimization the DIIS algorithm is used. This algorithm builds an approximation of the Hessian matrix and converges usually faster than the conjugate gradient algorithm. It is however recommended to set the independent degrees of freedom manually. *EDIFFG determines when to terminate the relaxation. Positive values: energy change between steps must be less than the value set by EDIFFG. Negative values: .

Download

H2O.tgz