About MSA 2.0 and MSA 2.0.1 (latest version)

MSA 2.0.1 is a software that generates permutationally invariant polynomials (PIPs) and gradients and optionally does a fit to electronic energies and gradients using PIPs.

The detailed theory is discussed in the references listed at the end. More information and a tutorial video can be found in the Tutorial.txt file and at https://scholarblogs.emory.edu/bowman/msa.

Prerequisites

For PIPs

1. C++ compiler;
2. Python3 and Perl;

For fits

4. Fortran 90
5. LAPACK library.

Credits

Original MSA code: Zhen Xie

Using gradient in the fit: Chen Qu

Python Wrapper: Qingfeng (Kee) Wang

References

1. Xie, Z., Bowman, J.M. Permutationally Invariant Polynomial Basis for Molecular Energy Surface Fitting via Monomial Symmetrization. J. Chem. Theory Comput. 2010, 6, 26-34.
2. Nandi, A. Qu, Chen, Bowman, J.M. Using Gradients in Permutationally Invariant Polynomial Potential Fitting: A Demonstration for CH4 Using as Few as 100 Configurations, J. Chem. Theory Comput. 2019, 15, 2826-2835