Communication: orbital instabilities and triplet states from time-dependent density functional theory and long-range corrected functionals

John S Sears; Thomas Koerzdoerfer; Cai-Rong Zhang; Jean-Luc Brédas

doi:10.1063/1.3656734

Communication: orbital instabilities and triplet states from time-dependent density functional theory and long-range corrected functionals

J Chem Phys. 2011 Oct 21;135(15):151103. doi: 10.1063/1.3656734.

Authors

John S Sears¹, Thomas Koerzdoerfer, Cai-Rong Zhang, Jean-Luc Brédas

Affiliation

¹ School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.

PMID: 22029290
DOI: 10.1063/1.3656734

Abstract

Long-range corrected hybrids represent an increasingly popular class of functionals for density functional theory (DFT) that have proven to be very successful for a wide range of chemical applications. In this Communication, we examine the performance of these functionals for time-dependent (TD)DFT descriptions of triplet excited states. Our results reveal that the triplet energies are particularly sensitive to the range-separation parameter; this sensitivity can be traced back to triplet instabilities in the ground state coming from the large effective amounts of Hartree-Fock exchange included in these functionals. As such, the use of standard long-range corrected functionals for the description of triplet states at the TDDFT level is not recommended.