# An integral-factorized implementation of the driven similarity renormalization group second-order multireference perturbation theory

## Abstract

We report an efficient implementation of a second-order multireference perturbation theory based on the driven similarity renormalization group (DSRG-MRPT2) [C. Li and F. A. Evangelista, J. Chem. Theory Comput. 11, 2097 (2015)]. Our implementation employs factorized two-electron integrals to avoid storage of large four-index intermediates. It also exploits the block structure of the reference density matrices to reduce the computational cost to that of second-order Møller–Plesset perturbation theory. Our new DSRG-MRPT2 implementation is benchmarked on ten naphthyne isomers using basis sets up to quintuple-ζ quality. We find that the singlet-triplet splittings (Δ{sub ST}) of the naphthyne isomers strongly depend on the equilibrium structures. For a consistent set of geometries, the Δ{sub ST} values predicted by the DSRG-MRPT2 are in good agreements with those computed by the reduced multireference coupled cluster theory with singles, doubles, and perturbative triples.

- Authors:

- Publication Date:

- OSTI Identifier:
- 22657806

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Chemical Physics

- Additional Journal Information:
- Journal Volume: 144; Journal Issue: 20; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COMPUTER CALCULATIONS; DENSITY MATRIX; DISTURBANCES; IMPLEMENTATION; PERTURBATION THEORY; RENORMALIZATION

### Citation Formats

```
Hannon, Kevin P., Li, Chenyang, and Evangelista, Francesco A., E-mail: francesco.evangelista@emory.edu.
```*An integral-factorized implementation of the driven similarity renormalization group second-order multireference perturbation theory*. United States: N. p., 2016.
Web. doi:10.1063/1.4951684.

```
Hannon, Kevin P., Li, Chenyang, & Evangelista, Francesco A., E-mail: francesco.evangelista@emory.edu.
```*An integral-factorized implementation of the driven similarity renormalization group second-order multireference perturbation theory*. United States. doi:10.1063/1.4951684.

```
Hannon, Kevin P., Li, Chenyang, and Evangelista, Francesco A., E-mail: francesco.evangelista@emory.edu. Sat .
"An integral-factorized implementation of the driven similarity renormalization group second-order multireference perturbation theory". United States. doi:10.1063/1.4951684.
```

```
@article{osti_22657806,
```

title = {An integral-factorized implementation of the driven similarity renormalization group second-order multireference perturbation theory},

author = {Hannon, Kevin P. and Li, Chenyang and Evangelista, Francesco A., E-mail: francesco.evangelista@emory.edu},

abstractNote = {We report an efficient implementation of a second-order multireference perturbation theory based on the driven similarity renormalization group (DSRG-MRPT2) [C. Li and F. A. Evangelista, J. Chem. Theory Comput. 11, 2097 (2015)]. Our implementation employs factorized two-electron integrals to avoid storage of large four-index intermediates. It also exploits the block structure of the reference density matrices to reduce the computational cost to that of second-order Møller–Plesset perturbation theory. Our new DSRG-MRPT2 implementation is benchmarked on ten naphthyne isomers using basis sets up to quintuple-ζ quality. We find that the singlet-triplet splittings (Δ{sub ST}) of the naphthyne isomers strongly depend on the equilibrium structures. For a consistent set of geometries, the Δ{sub ST} values predicted by the DSRG-MRPT2 are in good agreements with those computed by the reduced multireference coupled cluster theory with singles, doubles, and perturbative triples.},

doi = {10.1063/1.4951684},

journal = {Journal of Chemical Physics},

issn = {0021-9606},

number = 20,

volume = 144,

place = {United States},

year = {2016},

month = {5}

}