IALGO: Difference between revisions
No edit summary |
No edit summary |
||
| Line 3: | Line 3: | ||
Description: {{TAG|IALGO}} selects the algorithm used to optimize the orbitals. | Description: {{TAG|IALGO}} selects the algorithm used to optimize the orbitals. | ||
'''Mind''': We strongly urge the users to select the algorithms via {{TAG|ALGO}}. Algorithms other than those available via {{TAG|ALGO}} are subject to instabilities. | |||
---- | ---- | ||
*{{TAG|IALGO}}=-1: Performance test. | *{{TAG|IALGO}}=-1: Performance test. | ||
:VASP does not perform an actual calculation, only some important parts of the program will be executed and the timing for each part is printed out at the end. | :VASP does not perform an actual calculation, only some important parts of the program will be executed and the timing for each part is printed out at the end. | ||
Revision as of 13:39, 31 January 2011
IALGO = -1 | 2-4 | 5-8 | 15-18 | 28 | 38 | 44-48 | 53-58
| Default: IALGO | = 8 | for VASP.4.4 and older |
| = 38 | else (if ALGO is not set) |
Description: IALGO selects the algorithm used to optimize the orbitals.
Mind: We strongly urge the users to select the algorithms via ALGO. Algorithms other than those available via ALGO are subject to instabilities.
- IALGO=-1: Performance test.
- VASP does not perform an actual calculation, only some important parts of the program will be executed and the timing for each part is printed out at the end.
- IALGO=5-8: Conjugate gradient algorithms.
- Optimize each band iteratively using a conjugate gradient algorithm. Subspace-diagonalization before conjugate gradient algorithm. The conjugate gradient algorithm is used to optimize the eigenvalue of each band.
- IALGO=8 (VASP-releases older than VASP.4.5) is always fastest, IALGO=5-7 are only implemented for test purposes.
- Please mind, that IALGO=8 is not supported as of VASP.4.5, since M. Teter, Corning and M. Payne hold a patent on this algorithm.
- Kosugi algorithm (special blocked-Davidson iteration scheme). This algorithm is the default in VASP.4.6 and VASP.5.X. It optimizes a subset of NSIM bands simultaneously. The optimized bands are kept orthogonal to all other bands. If problems are encountered with the algorithm, try to decrease NSIM. Such problems are encountered, if linear dependencies develop in the search space. By reducing NSIM the rank of the search space is decreased.