# Software

### mrh

*mrh* is a Python3 program which implements the density matrix embedding theory (DMET), localized active space self-consistent fields (LASSCF), and multi-configurational pair-density functional theory (MC-PDFT) methods utilizing PYSCF as a quantum-chemistry backend. It is available at

For more details about *PYSCF*, see

https://github.com/sunqm/pyscf

http://sunqm.github.io/pyscf/

“PYSCF: Python-based simulations of chemistry framework“, Q. Sun, T. C. Berkelbach, N. S. Blunt, G. H. Booth, S. Guo, Z. Li, J. Liu, J. D. McClain, E. R. Sayfutyarova, S. Sharma, S. Wouters, G. K.-L. Chan,WIREs Comput. Mol. Sci.2018,8, e1340.

*mrh* is licensed under GNU General Public License v2.0. It is based on a fork of *QC-DMET: a python implementation of density matrix embedding theory for ab initio quantum chemistry* by Sebastian Wouters, which is also licensed under GPL v2.0 and is available at

as well as CAS-DMET by Hung Pham, which is available at

The DMET implementation is largely as described in

“A Practical Guide to Density Matrix Embedding Theory in Quantum Chemistry,“ S. Wouters, C. A. Jiménez-Hoyos, Q. Sun, and G. K.-L. Chan, J. Chem. Theory Comput.

2016,12, 2706.

The LASSCF implementation is as described in

“Exactly-embedded multiconfigurational self-consistent field theory using density matrix embedding: the localized active space self-consistent field method,“ M. R. Hermes and L. Gagliardi, arxiv:1810.03266 [physics.chem-ph], 2018.

The CAS-DMET implementation is as described in

H. Q. Pham, V. Bernales, and L. Gagliardi, “Can Density Matrix Embedding Theory with the Complete Activate Space Self-Consistent Field Solver Describe Single and Double Bond Breaking in Molecular Systems?“,

J. Chem. Theory Comput.,14,2018, pp 1960–1968 DOI: 10.1021/acs.jctc.7b01248