An efficient matrix-matrix multiplication based antisymmetric tensor contraction engine for general order coupled cluster.
In this paper, we present an efficient implementation of general tensor contractions, which is part of a new coupled-cluster program. The tensor contractions, used to evaluate the residuals in each coupled-cluster iteration are particularly important for the performance of the program. We developed a generic procedure, which carries out contractions of two tensors irrespective of their explicit structure. It can handle coupled-cluster-type expressions of arbitrary excitation level. To make the contraction efficient without loosing flexibility, we use a three-step procedure. First, the data contained in the tensors are rearranged into matrices, then a matrix-matrix multiplication is performed, and finally the result is backtransformed to a tensor. The current implementation is significantly more efficient than previous ones capable of treating arbitrary high excitations.
Hanrath
Michael
M
Institute for Theoretical Chemistry, University of Cologne, Greinstrasse 4, 50939 Cologne, Germany. michael.hanrath@uni-koeln.de
Engels-Putzka
Anna
A