Calibrating quantum chemistry: A multi-teraflop, parallel-vector, full-configuration interaction program for the Cray-X1

We describe an efficient parallel and vector algorithm for solving huge eigen-vector problems in quantum chemistry. An automatically adaptive, single-vector, iterative diagonalization method was also developed to reduce the memory requirement and avoid an I/O bottleneck. Our initial full-configuration interaction calculation solved for an eigenvector with 65 billion coefficients and was performed on 432 MSPs of the Oak Ridge National Laboratory Cray-X1. One matrixvector multiplication took about 4 minutes, with 25 iterations being required for a tightly converged result. The aggregate performance was 3.4TFLOP/s (62% of peak speed).