Vectorizing a sequence of conditional branches: The calculation of the class index of twoelectron repulsion integrals on cray computers
Abstract
The relative advantages of processing a supermatrix or a twoelectron integral file for the vectororiented computation of twoelectron interaction matrices in ab initio quantum chemical calculations are discussed briefly. It is concluded that the supermatrix formalism is less appropriate for large molecules. Two vector algorithms are presented for the calculation of the class index characterizing each twoelectron repulsion integral. Benchmark tests have been carried out on a CRAY2 computer; the timings for the new vector algorithms and for the standard scalar computations are reported for the two presently available versions of the CRAY2 FORTRAN compiler (CFT 77 and CFT2).
 Publication:

Computer Physics Communications
 Pub Date:
 February 1988
 DOI:
 10.1016/00104655(88)900380
 Bibcode:
 1988CoPhC..48..175E