INCAR: Difference between revisions
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===DIIS algorithm (IBRION=1)=== | ====RMM-DIIS algorithm (IBRION=1)==== | ||
Converges fast in systems that: | |||
Are close to a energy minimum (or maximum), with low degrees of freedom. The algorithm builds up an approximation of the Hessian matrix, taking the last NFREE steeps. | |||
it requires very accurate forces, otherwise it will fail to converge. An efficient way to achieve this is to set NELMIN to a value between 4 and 8 (for simple bulk materials 4 is usually adequate, whereas 8 might be required for complex surfaces where the charge density converges very slowly). This forces a minimum of 4 to 8 electronic steps between each ionic step, and guarantees that the forces are well converged at each step. | |||
===Transition state optimization (IBRION=44)=== | For more information: [http://dx.doi.org/10.1016/0009-2614(80)80396-4]. [http://cms.mpi.univie.ac.at/vasp/vasp/IBRION_1_I.html] | ||
====Conjugated Gradient algorithm (IBRION=2)==== | |||
====Damped MD and QUICKMIN (IBRION=3)==== | |||
====Transition state optimization (IBRION=44)==== | |||
==Others ionic updates== | ==Others ionic updates== | ||
Revision as of 14:55, 23 October 2012
By controling some parameters in the INCAR file, you can greatly increase the efficiency of your calculations.
Basic parameters
Ionic movement parameters
You can find more information about this topic in the VASP manual [1]
Ionic relaxation
RMM-DIIS algorithm (IBRION=1)
Converges fast in systems that:
Are close to a energy minimum (or maximum), with low degrees of freedom. The algorithm builds up an approximation of the Hessian matrix, taking the last NFREE steeps.
it requires very accurate forces, otherwise it will fail to converge. An efficient way to achieve this is to set NELMIN to a value between 4 and 8 (for simple bulk materials 4 is usually adequate, whereas 8 might be required for complex surfaces where the charge density converges very slowly). This forces a minimum of 4 to 8 electronic steps between each ionic step, and guarantees that the forces are well converged at each step.
For more information: [2]. [3]
Conjugated Gradient algorithm (IBRION=2)
Damped MD and QUICKMIN (IBRION=3)
Transition state optimization (IBRION=44)
Others ionic updates
Molecular Dynamics (MD) (IBRION=0)
See Molecular Dynamics with VASP