Active-space selection and CASSCF
Research context
research method · established · As of 2026-10-10
CAS-CI solves the configuration problem within a selected active orbital/electron space; CASSCF also optimizes the orbital partition.
Key knowledge
CAS-CI solves the configuration problem within a selected active orbital/electron space; CASSCF also optimizes the orbital partition. Correlation outside that space is incomplete, and combinatorial growth forces explicit active-space choices and convergence tests.
Conditions and scope
- Include orbitals needed for the competing states/bond changes; state averaging and orbital optimization do not guarantee the globally best chemically relevant active space.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Q-Chem 7.0: Complete active space introduction and theory: Section 6.20.1: active/inactive/virtual spaces, orbital optimization and combinatorial scaling (relevant full-text sections)
2026-10-10 · Bounded author source inspection of active-space selection and casscf, including the stated conditions; independent branch review is recorded separately.
Entry details
Permanent link to this entry ↗- Record identity
- res-chem-active-space
- Revision
- research.1
- Structured reference record
- Postgraduate & research reference