Superposition of Fragment Excitations for Excited States of Large Clusters with Application to Helium Clusters

Kristina D Closser; Qinghui Ge; Yuezhi Mao; Yihan Shao; Martin Head-Gordon

doi:10.1021/acs.jctc.5b00703

Superposition of Fragment Excitations for Excited States of Large Clusters with Application to Helium Clusters

J Chem Theory Comput. 2015 Dec 8;11(12):5791-803. doi: 10.1021/acs.jctc.5b00703. Epub 2015 Nov 20.

Authors

Kristina D Closser^{1

2}, Qinghui Ge^{1

2}, Yuezhi Mao¹, Yihan Shao³, Martin Head-Gordon^{1

2}

Affiliations

¹ Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California , Berkeley, California 94720, United States.
² Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
³ Q-Chem, Inc., 6601 Owens Drive, Suite 105, Pleasanton, California 94588, United States.

PMID: 26609558
DOI: 10.1021/acs.jctc.5b00703

Abstract

We develop a local excited-state method, based on the configuration interaction singles (CIS) wave function, for large atomic and molecular clusters. This method exploits the properties of absolutely localized molecular orbitals (ALMOs), which strictly limits the total number of excitations, and results in formal scaling with the third power of the system size for computing the full spectrum of ALMO-CIS excited states. The derivation of the equations and design of the algorithm are discussed in detail, with particular emphasis on the computational scaling. Clusters containing ∼500 atoms were used in evaluating the scaling, which agrees with the theoretical predictions, and the accuracy of the method is evaluated with respect to standard CIS. A pioneering application to the size dependence of the helium cluster spectrum is also presented for clusters of 25-231 atoms, the largest of which results in the computation of 2310 excited states per sampled cluster geometry.