PyQMC: an all-Python real-space quantum Monte Carlo module in PySCF

PyQMC is a Python-based package for high accuracy correlated electron calculations using quantum Monte Carlo (QMC) in real space. PyQMC implements variational Monte Carlo (VMC) and fixed node diffusion Monte Carlo (DMC) for ground and excited states of molecules and solids, and supports computation of a number of properties, in particular including one- and two-particle reduced density matrices.

Tight integration with the PySCF [1, 2] environment allows for simple comparison between QMC calculations and other many-body wave function techniques, as well as access to high accuracy trial wave functions. The all-Python code enables fast development of new techniques and flexible, complex workflows, such as the recent work from our group on QMC excited states.[3] Parallelization is implemented in a flexible way, so that the same code can be used on HPC or cloud resources; similarly, the same code runs with or without GPUs.

The code is freely available at https://github.com/WagnerGroup/pyqmc and on the Python Package Index (pip).

1. Q. Sun, et.al. (2018). WIREs Comput. Mol. Sci., 8: e1340. doi:10.1002/wcms.1340

2. Q. Sun, et. al. (2020). J. Chem. Phys., 153, 024109 (2020). doi:10.1063/5.0006074.

3. S. Pathak, B. Busemeyer, J. N. B. Rodrigues, and L. K. Wagner, J. Chem. Phys. 154, 034101 (2021); doi.org/10.1063/5.0030949