Identification of relevant configurations in a configuration interaction calculation is important not only for a compact representation of CI wave function but also for the efficient implementation of the CI method. Screening of configuration can be performed using various schemes including, energy-based criterion, perturbation theory, and filter-diagonalization method (both time-dependent and time-independent versions). This talk will focus on configuration screening using explicitly correlated function. The central idea of this approach is to project an explicitly correlated wavefunction (identical to the one used in variational Monte Carlo) in a finite dimensional determinantal space and identify a set of dominant configurations. We have applied this method for both restricted configuration interaction (CISD, CISDTQ) and full configuration interaction calculations. The results for ground and excited states energies for the restricted CI calculations will be presented for 2nd row molecules and comparison with literature data will be presented. For performing FCI calculations using the configuration screening, we have implemented the screening technique in the Monte Carlo Configuration Interaction (MCCI) method by Greer et al.  The screening has allowed us to substantially reduce the number of connected determinant in the CI procedure. In this talk, FCI calculation on the ground and excited potential energy curves for C2 dissociate will be presented and the results will be compared with the full configuration interaction quantum Monte Carlo (FCIQMC) by Alavi et al.[1]. J. Geer, JCP 103 , 1821 (1995)[2]. G. H. Booth, D. C. Cleland, A. J. Thom, and A. Alavi, JCP, 135 , 084104 (2011)[3]. M. G. Bayne, J. Drogo, and A. Chakraborty, PRA, 89 , 032515 (2014)

Configuration screen using explicitly correlation function for ground and excited state energies

248th National Meeting (2014)

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