Improving upon CCSD„T...: CCSD„T.... II. Stationary formulation and derivatives
نویسندگان
چکیده
Analytical derivatives are formulated and implemented for the CCSD T method. As the historically first size-extensive and orbitally invariant extension of coupled-cluster CC theory to exploit the left-hand ground state eigenvector, it offers a vastly better treatment of bond breaking than does CCSD T , and points the way toward further generalizations of single-reference CC theory that enhance its accuracy away from equilibrium geometries. Application to diatomic force curves and transition states of several well-characterized reactions are made. Surprisingly, despite CCSD T describing bond breaking much better than CCSD T , for transition states both methods are extremely close in both structures and activation barriers. Force curves, however, demonstrate the overall superiority of CCSD T . © 2008 American Institute of Physics. DOI: 10.1063/1.2830237
منابع مشابه
Improving upon CCSD„T...: CCSD„T.... I. Potential energy surfaces
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