Abstract
Use of orthogonalized Hartree product (OHP) orbitals as the reference orbitals in coupled‐cluster (cc) calculations is presented. Since such orbitals are determined without exchange, they provide as “classical” a description as possible. The OHP orbitals were generated by implementing Harris's formulation of the original Hartree method. Some computational considerations of the formulation are discussed. A critical evaluation of the OHP method as an orbital localization scheme is presented. The OHP orbitals were used as the reference in CCD and CCSD calculations and compared with corresponding Hartree‐Fock (HF) reference CC results. The average variation of localized Hartree product (LHP) reference CCSD energy from that of the HF reference is 0.83 kcal/mol, whereas for CCD, the average variation is 234 kcal/mol, indicating the importance of single‐excitation effects in CC calculations with non‐HF references. © 1994 John Wiley & Sons, Inc.
Original language | English |
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Pages (from-to) | 559-573 |
Number of pages | 15 |
Journal | International Journal of Quantum Chemistry |
Volume | 49 |
Issue number | 5 |
DOIs | |
State | Published - Feb 15 1994 |
Externally published | Yes |