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| general_hints_-_frequently_asked_questions [2025/05/28 09:14] – FAQ: how do I print all orbital coefficients doll | general_hints_-_frequently_asked_questions [2025/07/15 11:08] (current) – [In a nutshell: how to start] doll | ||
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| * W.J. Hehre, L. Radom, P.v.R. Schleyer, and J.A. Pople: Ab initio molecular orbital theory (Wiley, New York, 1986) | * W.J. Hehre, L. Radom, P.v.R. Schleyer, and J.A. Pople: Ab initio molecular orbital theory (Wiley, New York, 1986) | ||
| * W. Kutzelnigg: Einführung in die Theoretische Chemie (Wiley-VCH, Weinheim, 2001) | * W. Kutzelnigg: Einführung in die Theoretische Chemie (Wiley-VCH, Weinheim, 2001) | ||
| + | |||
| + | ==== In a nutshell: how to start ==== | ||
| + | |||
| + | Beginners should start with Hartree-Fock (basic theory, set up an input for HF, understanding the wf-card input and so on, try out basis sets, inspect orbitals); then one may: \\ | ||
| + | - either pursue single-reference methods such as MP2, CCSD and variants \\ | ||
| + | - or progress to MCSCF (MULTI) : wf-card, occ, closed, frozen card etc; then methods such as MRCI \\ | ||
| + | |||
| + | After being familiar with these methods, one may explore more sophisticated tools which rely on them.\\ | ||
| + | |||
| + | DFT is in many parts similar to Hartree-Fock concerning the input. | ||
| + | |||
| + | One should start with a basic input and then gradually increase complexity; it is not a good idea to start with | ||
| + | a complicated input and then change input parameters without any knowledge what these parameters are meant for. | ||
| + | Break problems into small pieces, and try to solve the smaller problems. | ||
| + | |||
| + | A more extended introduction how to use Molpro is in [[quickstart|this section of the manual]]. | ||
| + | |||
| + | Introductory [[https:// | ||
| ==== Miscellaneous ==== | ==== Miscellaneous ==== | ||
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| * When excited states are computed, then the preceding MCSCF should be state averaged, and include the excited states so that the orbitals from which the MRCI starts are reasonable. E.g. '' | * When excited states are computed, then the preceding MCSCF should be state averaged, and include the excited states so that the orbitals from which the MRCI starts are reasonable. E.g. '' | ||
| * MCSCF and MRCI are not black-box like, and e.g. a visualisation of the MCSCF orbitals will help to set up the active space. | * MCSCF and MRCI are not black-box like, and e.g. a visualisation of the MCSCF orbitals will help to set up the active space. | ||
| + | |||
| + | ==== Limit of 32 active orbitals ==== | ||
| + | |||
| + | There is a limit of at most 32 active orbitals which is unlikely to be increased in the near future, see | ||
| + | [[https:// | ||
| + | |||
| + | ==== Print all orbital coefficients instead of those which are above the default threshold ==== | ||
| + | |||
| + | use: '' | ||
| + | |||
| ==== molpro: No such file or directory ==== | ==== molpro: No such file or directory ==== | ||
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| - | ==== print all orbital coefficients instead of those which are above the default threshold ==== | ||
| - | use: '' | ||
| ==== Hardware ==== | ==== Hardware ==== | ||