Efficient computation of Hamiltonian matrix elements between non-orthogonal Slater determinants
We present an efficient numerical method for computing Hamiltonian matrix elements between non-orthogonal Slater determinants, focusing on the most time-consuming component of the calculation that involves a sparse array. In the usual case where many matrix elements should be calculated, this computation can be transformed into a multiplication of dense matrices. It is demonstrated that the present method based on the matrixmatrix multiplication attains ?80% of the theoretical peak performance measured on systems equipped with modern microprocessors, a factor of 510 better than the normal method using indirectly indexed arrays to treat a sparse array. The reason for such different performances is discussed from the viewpoint of memory access.
quantum many-body problem hamiltonian overlap blas