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The multifacet graphically contracted function method. I. Formulation and implementation
DOI:10.1063/1.4890734.png)
Abstract
En 中文
The basic formulation for the multifacet generalization of the graphically contracted function (MFGCF) electronic structure method is presented. The analysis includes the discussion of linear dependency and redundancy of the arc factor parameters, the computation of reduced density matrices, Hamiltonian matrix construction, spin-density matrix construction, the computation of optimization gradients for single-state and state-averaged calculations, graphical wave function analysis, and the efficient computation of configuration state function and Slater determinant expansion coefficients. Timings are given for Hamiltonian matrix element and analytic optimization gradient computations for a range of model problems for full-CI Shavitt graphs, and it is observed that both the energy and the gradient computation scale as O(N(2)n(4)) for N electrons and n orbitals. The important arithmetic operations are within dense matrix-matrix product computational kernels, resulting in a computationally efficient procedure. An initial implementation of the method is used to present applications to several challenging chemical systems, including N-2 dissociation, cubic H-8 dissociation, the symmetric dissociation of H2O, and the insertion of Be into H-2. The results are compared to the exact full-CI values and also to those of the previous single-facet GCF expansion form. (C) 2014 AIP Publishing LLC.
Keywords:
MATRIX RENORMALIZATION-GROUP
CORRELATED MOLECULAR CALCULATIONS
GAUSSIAN-BASIS SETS
CONFIGURATION-INTERACTION
PROGRAM SYSTEM
FULL CI
DENSITY
OPTIMIZATION
GRADIENTS
ALGORITHM
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