title: An efficient parallel algorithm for the calculation of unrestricted canonical MP2 energies.
abstract: We present details of our efficient implementation of full accuracy unrestricted open-shell second-order canonical Møller-Plesset (MP2) energies, both serial and parallel. The algorithm is based on our previous restricted closed-shell MP2 code using the Saebo-Almlöf direct integral transformation. Depending on system details, UMP2 energies take from less than 1.5 to about 3.0 times as long as a closed-shell RMP2 energy on a similar system using the same algorithm. Several examples are given including timings for some large stable radicals with 90+ atoms and over 3600 basis functions.
authors.affiliation: Parallel Quantum Solutions, Fayetteville, Arkansas 72703, USA. baker@pqs-chem.com.
authors.forename: Jon
authors.initials: J
authors.lastname: Baker
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Wolinski