title: Highly efficient implementation of pseudospectral time-dependent density-functional theory for the calculation of excitation energies of large molecules.
abstract: We have developed and implemented pseudospectral time-dependent density-functional theory (TDDFT) in the quantum mechanics package Jaguar to calculate restricted singlet and restricted triplet, as well as unrestricted excitation energies with either full linear response (FLR) or the Tamm-Dancoff approximation (TDA) with the pseudospectral length scales, pseudospectral atomic corrections, and pseudospectral multigrid strategy included in the implementations to improve the chemical accuracy and to speed the pseudospectral calculations. The calculations based on pseudospectral time-dependent density-functional theory with full linear response (PS-FLR-TDDFT) and within the Tamm-Dancoff approximation (PS-TDA-TDDFT) for G2 set molecules using B3LYP/6-31G*(*) show mean and maximum absolute deviations of 0.0015 eV and 0.0081 eV, 0.0007 eV and 0.0064 eV, 0.0004 eV and 0.0022 eV for restricted singlet excitation energies, restricted triplet excitation energies, and unrestricted excitation energies, respectively; compared with the results calculated from the conventional spectral method. The application of PS-FLR-TDDFT to OLED molecules and organic dyes, as well as the comparisons for results calculated from PS-FLR-TDDFT and best estimations demonstrate that the accuracy of both PS-FLR-TDDFT and PS-TDA-TDDFT. Calculations for a set of medium-sized molecules, including Cn fullerenes and nanotubes, using the B3LYP functional and 6-31G(**) basis set show PS-TDA-TDDFT provides 19- to 34-fold speedups for Cn fullerenes with 450-1470 basis functions, 11- to 32-fold speedups for nanotubes with 660-3180 basis functions, and 9- to 16-fold speedups for organic molecules with 540-1340 basis functions compared to fully analytic calculations without sacrificing chemical accuracy. The calculations on a set of larger molecules, including the antibiotic drug Ramoplanin, the 46-residue crambin protein, fullerenes up to C540 and nanotubes up to 14×(6,6), using the B3LYP functional and 6-31G(**) basis set with up to 8100 basis functions show that PS-FLR-TDDFT CPU time scales as N(2.05) with the number of basis functions. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Schrödinger Inc, 120 West 45th Street, Tower 45, 17th Floor, New York, New York, 10036.
authors.forename: Yixiang
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Schrödinger Inc, 120 West 45th Street, Tower 45, 17th Floor, New York, New York, 10036.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hughes
authors.affiliation: Schrödinger Inc, 120 West 45th Street, Tower 45, 17th Floor, New York, New York, 10036.
authors.forename: Dave
authors.initials: D
authors.lastname: Giesen
authors.affiliation: Schrödinger Inc, 120 West 45th Street, Tower 45, 17th Floor, New York, New York, 10036.
authors.forename: Mathew D
authors.initials: MD
authors.lastname: Halls
authors.affiliation: Schrödinger Inc, 8910 University Lane, Suite 270, San Diego, California, 92122.
authors.forename: Alexander
authors.initials: A
authors.lastname: Goldberg
authors.affiliation: Schrödinger, Plot No. 573, B & C, Road No. 1, Jubilee Hills, Hyderabad, Telangana, 5000096, India.
authors.forename: Tati Reddy
authors.initials: TR
authors.lastname: Vadicherla
authors.affiliation: Schrödinger, Sanali Infopark, 8-2-120/113, Banjara Hills, Hyderabad, Andhra Pradesh, 500034, India.
authors.forename: Madhavi
authors.initials: M
authors.lastname: Sastry
authors.affiliation: Schrödinger, Sanali Infopark, 8-2-120/113, Banjara Hills, Hyderabad, Andhra Pradesh, 500034, India.
authors.forename: Bhargav
authors.initials: B
authors.lastname: Patel
authors.affiliation: Schrödinger Inc, 245 First St. Riverview II, 18th Floor, Cambridge, Massachusetts, 02142.
authors.forename: Woody
authors.initials: W
authors.lastname: Sherman
authors.affiliation: Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York, 10027.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Weisman
authors.affiliation: Department of Chemistry, Columbia University, New York, New York, 10027.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Friesner
keywords: Tamm-Dancoff approximation; density-functional theory; pseudospectral; time-dependent density-functional theory