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| automated_construction_of_atomic_valence_active_spaces [2025/09/19 09:14] – [AVAS as independent program] doll | automated_construction_of_atomic_valence_active_spaces [2026/01/30 13:54] (current) – doll |
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| where //n// is the principal quantum number, and //type// is ''%%s, p, d%%'',…. Alternatively, individual components such as ''%%px, py, pz%%'', or ''%%d0, d1+, d1-, d2+, d2-%%'' can also be given, and then only the specified functions are used (otherwise all components are included). If the principal quantum number $n$ is given, the $n-l$’th atomic function of the given type will be used (e.g., for ''2s'' the second $s$-function, for ''2p'', the first $p$ function, for ''4d'' the second $d$ function). If $n$ is not given, the first function of the given type is used. | where //n// is the principal quantum number, and //type// is ''%%s, p, d%%'',…. Alternatively, individual components such as ''%%px, py, pz%%'', or ''%%d0, d1+, d1-, d2+, d2-%%'' can also be given, and then only the specified functions are used (otherwise all components are included). If the principal quantum number $n$ is given, the $n-l$’th atomic function of the given type will be used (e.g., for ''2s'' the second $s$-function, for ''2p'', the first $p$ function, for ''4d'' the second $d$ function). If $n$ is not given, the first function of the given type is used. |
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| From Molpro version 2022.2 $n$ is the principal quantum number, independent of how many orbitals are in peudopotentials (ECPs). This is different to earlier versions, were $n$ counted the number of orbitals outside the ECP. | From Molpro version 2022.2 $n$ is the principal quantum number, independent of how many orbitals are in pseudopotentials (ECPs). This is different to earlier versions, were $n$ counted the number of orbitals outside the ECP. |
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| Example: | Example: |
| A subsequent CASSCF (MULTI) calculation will automatically use the generated active space (unless specified otherwise) and use the AVAS orbitals (unless different orbitals are specified on a ''START'' directive). | A subsequent CASSCF (MULTI) calculation will automatically use the generated active space (unless specified otherwise) and use the AVAS orbitals (unless different orbitals are specified on a ''START'' directive). |
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| It is recommended to first do a CASSCI calculation using | It is recommended to first do a CASCI calculation using |
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| <code> | <code> |
| ====== AVAS within HF or KS ====== | ====== AVAS within HF or KS ====== |
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| In this case the converged HF orbitals are used, and the closed-shell valence orbitals (excluding core orbitals) and virtual orbitals are projected independently, and the active orbitals resulting from these two subspaces are determined. IF ''OPEN=0'' (default in this case) the open-shell orbitals remain unchanged and are subsequently added to the active space. In this way, a CASSCI using the generated active space will never give a higher energy than the RHF energy, and according to preliminary experience this yields the best starting orbitals for a subsequent CASSCF calculation. The inactive, active and virtual subspaces are made pseudo-canonical by block-diagonalizing the Fock matrix. | In this case the converged HF orbitals are used, and the closed-shell valence orbitals (excluding core orbitals) and virtual orbitals are projected independently, and the active orbitals resulting from these two subspaces are determined. IF ''OPEN=0'' (default in this case) the open-shell orbitals remain unchanged and are subsequently added to the active space. In this way, a CASCI using the generated active space will never give a higher energy than the RHF energy, and according to preliminary experience this yields the best starting orbitals for a subsequent CASSCF calculation. The inactive, active and virtual subspaces are made pseudo-canonical by block-diagonalizing the Fock matrix. |
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| The general input is | The general input is |