|Organization or Institution||Florida State University|
Efficient integrators for time-dependent coupled-cluster theory
Brandon C. Cooper and A. Eugene DePrince
Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306
This work considers the short iterative Lanczos (SIL) and asymmetric short iterative Lanczos (ASIL) methods and their utility as numerical integrators within time-dependent (TD) equation of motion (EOM) couple-cluster (CC) theory. The performance of the integrators is assessed by comparing linear absorption spectra computed at the second order approximate CC (CC2) level of theory, against spectra obtained with fourth order Runge-Kutta (RK4) integration. Both Lanczos methods offer a significant improvement over RK4 for TD-EOM-CC simulations; the number of sigma vector builds required to converge a spectrum is reduced by roughly a factor of 10 for the SIL method and 4 for the ASIL method. We also demonstrate that the SIL method produces spectra of the same quality as ASIL method at half the computational cost.