1. Efficient Method for Calculating Effective Core Potential Integrals.
- Author
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McKenzie, Simon C., Epifanovsky, Evgeny, Barca, Giuseppe M. J., Gilbert, Andrew T. B., and Gill, Peter M. W.
- Subjects
- *
CONDUCTION electrons , *INTEGRALS , *ANALYTICAL chemistry , *MOLECULAR structure , *ERROR analysis in mathematics - Abstract
Effective core potential (ECP) integrals are among the most difficult one-electron integrals to calculate due to the projection operators. The radial part of these operators may include r0, r-1, and r-2 terms. For the r0 terms, we exploit a simple analytic expression for the fundamental projected integral to derive new recurrence relations and upper bounds for ECP integrals. For the r-1 and r-2 terms, we present a reconstruction method that replaces these terms by a sum of r0 terms and show that the resulting errors are chemically insignificant for a range of molecular properties. The new algorithm is available in Q-Chem 5.0 and is significantly faster than the ECP implementations in Q-Chem 4.4, GAMESS (US) and Dalton 2016. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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