Analytic MP2 frequencies without fifth-order storage. Theory and application to bifurcated hydrogen bonds in the water hexamer
M Head-Gordon, T Head-Gordon - Chemical Physics Letters, 1994 - Elsevier
An obstacle to obtaining vibrational frequencies of large molecules via second-order Møller—
Plesset (MP2) theory has been the need to store transformed electron repulsion integral
derivatives in the molecular orbital (MO) basis. A semi-direct algorithm for eliminating this
fifth-order storage is described in which small batches of MO integral derivatives are made at
a time, their contributions to the MP2 second derivatives are evaluated, and then they are
discarded. No extra computation is required. We locate and characterize a transition …
Plesset (MP2) theory has been the need to store transformed electron repulsion integral
derivatives in the molecular orbital (MO) basis. A semi-direct algorithm for eliminating this
fifth-order storage is described in which small batches of MO integral derivatives are made at
a time, their contributions to the MP2 second derivatives are evaluated, and then they are
discarded. No extra computation is required. We locate and characterize a transition …