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Efficient calculation of integrals in mixed ramp-Gaussian basis sets

McKemmish, LK; (2015) Efficient calculation of integrals in mixed ramp-Gaussian basis sets. The Journal of Chemical Physics , 142 , Article 134104. 10.1063/1.4916314. Green open access

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Abstract

Algorithms for the efficient calculation of two-electron integrals in the newly developed mixed ramp-Gaussian basis sets are presented, alongside a Fortran90 implementation of these algorithms, RampItUp.These new basis sets have significant potential to (1) give some speed-up (estimated at up to 20% for large molecules in fully optimised code) to general-purpose Hartree-Fock (HF) and density functional theory quantum chemistry calculations, replacing all-Gaussian basis sets, and (2) give very large speed-ups for calculations of core-dependent properties, such as electron density at the nucleus, NMR parameters, relativistic corrections, and total energies, replacing the current use of Slater basis functions or very large specialised all-Gaussian basis sets for these purposes. This initial implementation already demonstrates roughly 10% speed-ups in HF/R-31G calculations compared to HF/6-31G calculations for large linear molecules, demonstrating the promise of this methodology, particularly for the second application. As well as the reduction in the total primitive number in R-31G compared to 6-31G, this timing advantage can be attributed to the significant reduction in the number of mathematically complex intermediate integrals after modelling each ramp-Gaussian basis-function-pair as a sum of ramps on a single atomic centre.

Type: Article
Title: Efficient calculation of integrals in mixed ramp-Gaussian basis sets
Open access status: An open access version is available from UCL Discovery
DOI: 10.1063/1.4916314
Publisher version: http://dx.doi.org/10.1063/1.4916314
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. © 2015 AIP Publishing LLC
Keywords: Basis sets, angular momentum, integration, density functional theory, recurrence relations.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/1531094
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