Multi-reference Brillouin-Wigner coupled-cluster method with a general model space

We describe a multi-reference Brillouin - Wigner coupled-cluster ( BWCC) method that employs a general model space ( GMS) by relying on the recently introduced C-conditions [ X. Li, J. Paldus. J. chem. Phys., 119, 5320 ( 2003).] This generalization preserves all the essential features of the standard complete model space ( CMS) BWCC method. This makes it possible to substantially reduce the dimension of the model space employed by keeping only important configurations and thus to minimize the computational cost. We also present the results of a preliminary numerical test using the cc-pVDZ model of the LiH molecule.