O dimer: Difference between revisions
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*The CG algorithm requires line minimizations along the search direction. This is done using a variant of Brent's algorithm. (Picture missing) | *The CG algorithm requires line minimizations along the search direction. This is done using a variant of Brent's algorithm. (Picture missing) | ||
**Trial step along search direction (gradient scaled by {{TAG|POTIM}}) | **Trial step along search direction (gradient scaled by {{TAG|POTIM}}) | ||
**Quadratic or cubic interpolation using energies and forces at <math> \mathbf{x}_{0} </math> and <math> \mathbf{x}_{1} </math> allows to determine the approximate minimum | **Quadratic or cubic interpolation using energies and forces at <math> \mathbf{x}_{0} </math> and <math> \mathbf{x}_{1} </math> allows to determine the approximate minimum | ||
Revision as of 13:14, 27 April 2017
Overview > O atom > O atom spinpolarized > O atom spinpolarized low symmetry > O dimer > CO > CO vibration > CO partial DOS > H2O >
H2O vibration > H2O molecular dynamics > Further things to try > List of tutorials
Task
Relaxation of the bond length of an dimer.
Input
POSCAR
O dimer 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) 2 ! number of atoms cart ! positions in cartesian coordinates 0 0 0 ! first atom 0 0 1.22 ! second atom
INCAR
SYSTEM = O2 dimer in a box ISMEAR = 0 ! Gaussian smearing ISPIN = 2 ! spin polarized calculation 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
Calculation
- We have selected in the INCAR file that geometry relaxation should be performed. In this case 5 ionic steps (NSW=5) should be done at most. For the relaxation a conjugate gradient (CG) algorithm is used (IBRION=2).
- The CG algorithm requires line minimizations along the search direction. This is done using a variant of Brent's algorithm. (Picture missing)
- Trial step along search direction (gradient scaled by POTIM)
- Quadratic or cubic interpolation using energies and forces at and allows to determine the approximate minimum
- Continue minimization, if app. minimum is not accurate enough
Download
To the list of examples or to the main page