| Both sides previous revision Previous revision Next revision | Previous revision |
| multireference_rayleigh_schroedinger_perturbation_theory [2026/02/23 08:54] – [Level shifts] werner | multireference_rayleigh_schroedinger_perturbation_theory [2026/02/27 10:46] (current) – fix broken link may |
|---|
| * **''SAVEH=''//record//** Record for saving the effective Hamiltonian in MS-CASPT2 calculations. If this is not given, a default record will be used (recommended). | * **''SAVEH=''//record//** Record for saving the effective Hamiltonian in MS-CASPT2 calculations. If this is not given, a default record will be used (recommended). |
| * **''INIT''** (logical) Initializes a MS-CASPT2 with single state reference functions, see section [[multireference Rayleigh Schrödinger perturbation theory#Multi-State CASPT2|Multi-State CASPT2]] | * **''INIT''** (logical) Initializes a MS-CASPT2 with single state reference functions, see section [[multireference Rayleigh Schrödinger perturbation theory#Multi-State CASPT2|Multi-State CASPT2]] |
| * **''IGNORE''** (logical) Flags an approximate gradient calculation without CP-CASPT2; see section [[multireference Rayleigh Schrödinger perturbation theory**CASPT2 gradients|CASPT2 gradients]] for details. | * **''IGNORE''** (logical) Flags an approximate gradient calculation without CP-CASPT2; see section [[multireference Rayleigh Schrödinger perturbation theory#CASPT2 gradients|CASPT2 gradients]] for details. |
| * **''PROPERTIES''** or **''PROP''** (logical, default true, ''RS2C'' only) Flag on whether the expectation values of properties are computed. By default dipole moments are always computed but this may be expensive in multi-state calculations. Pass ''NOPROP'' to skip the property calculation. | * **''PROPERTIES''** or **''PROP''** (logical, default true, ''RS2C'' only) Flag on whether the expectation values of properties are computed. By default dipole moments are always computed but this may be expensive in multi-state calculations. Pass ''NOPROP'' to skip the property calculation. |
| |
| ''STATE'',1,//root// | ''STATE'',1,//root// |
| |
| where //root// is the desired root (i.e., 2 for the first excited state). In this case the Fock operator used in the zeroth-order Hamiltonian is computed using the density for the given state. | where //root// is the desired root (i.e., 2 for the first excited state). In this case the Fock operator used in the zeroth-order Hamiltonian is computed using the density for the given state. Note that all states must have the same symmetry. |
| |
| 2) Alternatively, two or more states can be computed simultaneously, using | 2) Alternatively, two or more states can be computed simultaneously, using |
| |
| With the ''RS2C'' program the two modes can be mixed, e.g., in a 3-state calculation using the SS-SR-CASPT2 for one state and the MS-MR-CASPT2 for the other two states. | With the ''RS2C'' program the two modes can be mixed, e.g., in a 3-state calculation using the SS-SR-CASPT2 for one state and the MS-MR-CASPT2 for the other two states. |
| | |
| | Note that all states must have the same spin and spatial symmetry. |
| ==== Performing SS-SR-CASPT2 calculations ==== | ==== Performing SS-SR-CASPT2 calculations ==== |
| |