Reducing I/O costs for the eigenvalue procedure in large‐scale configuration interaction calculations

Several aspects of the matrix diagonalization method used for CI calculations in the COLUMBUS Program System are discussed, including a linear basis‐contraction algorithm and the use of a nonorthogonal expansion basis. Both of these features significantly reduce the I/O requirements during the iterations. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 1121–1125, 2002