High-spin coupled-cluster theory

P.. Knowles, C. Hampel, and H.-. Werner,/. Chem. Phys., 99, 5219 (1993). Coupled-Cluster Theory for High-Spin, Open-Shell Reference Wave Functions. 

C., and Werner, H.-J. (1993) Coupled cluster theory for high spin, open shell reference wave functions. J. Chem. Phys., 99, 5219 5227 (d) Watts, ).D., Gauss,... 

A time-dependent coupled cluster theory with unrestricted electron spins and full treatment of orbital rotation has been implemented to calculate the polarizabilities and dispersion coefficients. Illustration calculations on Li, Ar, HCl, CO, N2, O2, and H2O at the coupled cluster singles and doubles level have demonstrated the reliabihty of the method. Comparisons with HF and MP2 results have further shown the importance of high-order electron correlation effects whereas basis sets of the aug-cc-pVXZ family have been compared. 

High-spin open-shell coupled-cluster theory... 

T. D. Crawford, Ph.D. Thesis, University of Georgia, 1996. Many-Body Perturbation Theory and Perturbational Triple Excitation Corrections to the Coupled-Cluster Singles and Doubles Method for High-Spin Open-Shell Systems. 

In the last several years, we have developed coupled-cluster (CC) based quantum chemical methods (13), which are among the most accurate available in the field. Today, such methods are frequently those of choice when both high accuracy and wide applicability are required (14). In our CC efforts, we have generalized the ground state description of CC theory to that for excited states, via the equation-of-motion approach (extension for NMR spin-spin coupling... 

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