TurboTDDFT – A code for the simulation of molecular spectra using the Liouville–Lanczos approach to time-dependent density-functional perturbation theory

Abstract

We introduce turboTDDFT, an implementation of the Liouville–Lanczos approach to linearized time-dependent density-functional theory, designed to simulate the optical spectra of molecular systems made of up to several hundred atoms. turboTDDFT is open-source software distributed under the terms of the GPL as a component of Quantum ESPRESSO. As with other components, turboTDDFT is optimized to run on a variety of different platforms, from laptops to massively parallel architectures, using native mathematical libraries (LAPACK and FFTW) and a hierarchy of custom parallelization layers built on top of MPI. Program summaryProgram title: turboTDDFTCatalogue identifier: AEIX_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEIX_v1_0.htmlProgram obtainable from: CPC Program Library, Queenʼs University, Belfast, N. IrelandLicensing provisions: GNU General Public License V 2.0No. of lines in distributed program, including test data, etc.: 3 559 889No. of bytes in distributed program, including test data, etc.: 254 283 981Distribution format: tar.gzProgramming language: Fortran 95Computer: Any computer architectureOperating system: GNU/Linux, AIX, IRIX, Mac OS X, and other UNIX-like OSʼsClassification: 16.2, 16.6, 7.7External routines: turboTDDFT is a tightly integrated component of the Quantum ESPRESSO distribution and requires the standard libraries linked by it: BLAS, LAPACK, FFTW, MPI.Nature of problem: Calculation of the optical absorption spectra of molecular systems.Solution method: The dynamical polarizability of a system is expressed in terms of the resolvent of its Liouvillian super-operator within time-dependent density-functional theory, and calculated using a non-Hermitean Lanczos method, whose implementation does not require the calculation of any virtual states. Pseudopotentials (both norm-conserving and ultrasoft) are used in conjunction with plane-wave basis sets.Restrictions: Spin-restricted formalism. Linear-response regime. No hybrid functionals. Adiabatic XC kernels only.Unusual features: No virtual orbitals are used, nor even calculated. A single Lanczos recursion gives access to the whole optical spectrum.Additional comments: !!!!! The distribution file for this program is over 254 Mbytes and therefore is not delivered directly when download or E-mail is requested. Instead a html file giving details of how the program can be obtained is sent.Running time: From a few minutes for small molecules on serial machines up to many hours on multiple processors for complex nanosystems with hundreds of atoms.