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| the_nevpt2_program [2023/12/23 16:58] – [General considerations] werner | the_nevpt2_program [2024/01/08 13:24] (current) – external edit 127.0.0.1 |
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| ''DF-NEVPT2''. | ''DF-NEVPT2''. |
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| If you encounter an error exit due to non-zero Fock-matrix elements, the following can help: | ''If you encounter an error exit'' due to non-zero Fock-matrix elements, the following can help: |
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| * Save state-specific canonical or natural orbitals in multi, e.g. for the second state in symmetry 1: ''NATORB,2141.2,state=2.1''. Do this for each state you want to treat by NEVPT2 with a different record. Use in nevpt2 for state 2.1 ''ORBITAL=2141.2''. If you hit in multi the message "too many NATORB directives", you can use a subsequent CASCI calculation to add more NATORB directives. | * In state-averaged CASSCF calculations, save state-specific canonical or natural orbitals in multi, e.g. for the second state in symmetry 1: ''NATORB,2141.2,state=2.1''. Do this for each state you want to treat by NEVPT2 with a different record. If you hit in multi the message "too many NATORB directives", you can use a subsequent CASCI calculation to add more NATORB directives. |
| * Use the ''NOEXTRA'' directive in multi. | * Use the ''NOEXTRA'' directive in multi. |
| * Add in nevpt2 ''PSPACE,1; OPTION, NSTATI=n'', where n is the number of states you have optimized in multi for the current symmetry. | * Add in nevpt2 the directives: ''PSPACE,1; OPTION, NSTATI=n; ORBITAL=record'', where n is the number of states you have optimized in multi for the current symmetry, and record is the record on which you have saved the orbitals for the state under consideration (in fact, what matters is the state-specific Fock matrix, which is saved along with the orbitals). |
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