The coupled‐cluster single, double, and triple excitation model for open‐shell single reference functions

The CCSDT model for general single determinant reference functions for open and closed‐shell electronic states has been implemented for the first time and has been used to compute the electron affinity of the F atom, the CH2, 3B1–1A1 energy difference, and the ionization potentials of 1A1 CH2. The results compare very well with FCI and are markedly superior to those of simpler coupled‐cluster methods.

[1]  J. Cizek.  On the Correlation Problem in Atomic and Molecular Systems. Calculation of Wavefunction Components in Ursell-Type Expansion Using Quantum-Field Theoretical Methods , 1966 .

[2]  J. S. Binkley,et al.  Electron correlation theories and their application to the study of simple reaction potential surfaces , 1978 .

[3]  Rodney J. Bartlett,et al.  Many‐body perturbation theory, coupled‐pair many‐electron theory, and the importance of quadruple excitations for the correlation problem , 1978 .

[4]  R. Bartlett,et al.  A full coupled‐cluster singles and doubles model: The inclusion of disconnected triples , 1982 .

[5]  R. Bartlett,et al.  A coupled cluster approach with triple excitations , 1984 .

[6]  S. J. Cole,et al.  Towards a full CCSDT model for electron correlation , 1985 .

[7]  S. J. Cole,et al.  Singlet-triplet energy gap in methylene using many-body methods☆ , 1985 .

[8]  Benchmark full configuration‐interaction calculations on H2O, F, and F− , 1986 .

[9]  P. Taylor,et al.  A full CI treatment of the 1A1-3B1 separation in methylene , 1986 .

[10]  C. Bauschlicher,et al.  Full CI benchmark calculations for several states of the same symmetry , 1987 .

[11]  R. Bartlett,et al.  The full CCSDT model for molecular electronic structure , 1987 .

[12]  R. Bartlett,et al.  Towards a full CCSDT model for electron correlation. CCSDT-n models , 1987 .

[13]  Henry F. Schaefer,et al.  A new implementation of the full CCSDT model for molecular electronic structure , 1988 .

[14]  Rodney J. Bartlett,et al.  An open-shell spin-restricted coupled cluster method: application to ionization potentials in nitrogen , 1988 .

[15]  Rodney J. Bartlett,et al.  Analytic energy derivatives in many‐body methods. I. First derivatives , 1989 .

[16]  Multi-reference coupled-cluster methods for ionization potentials with partial inclusion of triple excitations , 1989 .