### Abstract

To treat large molecules with accurate ab initio quantum chemistry, reduced scaling correlated wave function methods are now commonly employed. Optimization of these wave functions in practice requires some approximation of the two-electron integrals. Both Cholesky decomposition (CD) and density fitting (DF) are widely used approaches to approximate these integrals. Here, we compare CD and DF for use in local multireference singles and doubles configuration interaction (LMRSDCI). DF-LMRSDCI provides less accurate total energies than CD-LMRSDCI, but both methods are accurate for energy differences. However, DF-LMRSDCI is significantly less computationally expensive than CD-LMRSDCI on the molecules tested, suggesting that DF-LMRSDCI is an efficient, often sufficiently accurate alternative to our previously reported CD-LMRSDCI method.

Original language | English (US) |
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Pages (from-to) | 5242-5251 |

Number of pages | 10 |

Journal | Journal of Chemical Theory and Computation |

Volume | 11 |

Issue number | 11 |

DOIs | |

State | Published - Nov 10 2015 |

### All Science Journal Classification (ASJC) codes

- Computer Science Applications
- Physical and Theoretical Chemistry

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## Cite this

*Journal of Chemical Theory and Computation*,

*11*(11), 5242-5251. https://doi.org/10.1021/acs.jctc.5b00762