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RESEARCH PRODUCT
The multi-state CASPT2 method
Per-åke MalmqvistLuis Serrano-andrésBjörn O. RoosJames P. Finleysubject
Multi stateAb initio multiple spawningChemistryAvoided crossingPotential curvesGeneral Physics and AstronomyPerturbation (astronomy)Applied mathematicsPhysical and Theoretical ChemistryAtomic physicsElectronic statesdescription
Abstract An extension of the multiconfigurational second-order perturbation approach CASPT2 is suggested, where several electronic states are coupled at second order via an effective-Hamiltonian approach. The method has been implemented into the MOLCAS-4 program system, where it will replace the single-state CASPT2 program. The accuracy of the method is illustrated through calculations of the ionic-neutral avoided crossing in the potential curves for LiF and of the valence-Rydberg mixing in the V-state of the ethylene molecule.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1998-05-01 | Chemical Physics Letters |