A calculation of spectroscopic parameters for hydrogen fluoride with multi-reference state-specific coupled-cluster method

The multi-reference state-specific coupled-cluster method with a complete-active-space reference (CASCC) developed by our group has been used to calculate the potential energy curves, spectroscopic parameters, and vibrational levels for the ground (X(1)Sigma(+)) and excited (B(1)Sigma(+)) states of (19)FH. The working algorithm for the CASCC method was derived with a computer-based automated approach that generates the CC energy and amplitude equations and the corresponding coupled-cluster diagrams. The spin-orbital sets for the CASCC calculations have been obtained using the complete-active-space self-consistentfield method (CASSCF). As determined by comparing the theoretical results with experimental ones reconstructed using the Rydberg-Klein-Reese method, the CASCC energies are better than those obtained with the CCSD and EOM-CCSD methods. (C) 2010 Elsevier B. V. All rights reserved.