MSTor Home Page

March 31, 2023

MSTor: A program for calculating partition functions, free energies, enthalpies, entropies, and heat capacities of complex molecules including torsional anharmonicity

Jingjing Zheng,
Gaussian, Inc., 340 Quinnipiac Street, Building 40,
Wallingford, CT 06492, USA

Wenqi Chen,
Center for Combustion Energy, Department of Energy and Power Engineering, and
Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,
Tsinghua University, Beijing 100084, China

Steven L. Mielke, Junwei Lucas Bao, Rubén Meana-Pañeda
Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute
University of Minnesota, Minneapolis, Minnesota 55455

Kenneth L. Clarkson,
IBM Almaden Research Center
San Jose, CA 95120

Xuefei Xu,
Center for Combustion Energy, Department of Energy and Power Engineering, and
Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,
Tsinghua University, Beijing 100084, China

and Donald G. Truhlar
Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute
University of Minnesota, Minneapolis, Minnesota 55455

Version information

MSTor manual:

MSTor 2023

manual

Abstract

MSTor is a computer program for calculating gas-phase molecular partition functions and thermodynamic functions (standard state energy, enthalpy, entropy, free energy, and heat capacity at constant pressure) as functions of temperature by the multi-structural approximation with torsional anharmonicity (MS-T). The MS-T method is especially designed for the convenient treatment of molecules with many conformational structures generated by internal rotations (torsions). The default method in MSTor is the multi-structural approximation with torsional anharmonicity, a coupled torsional potential, and delocalized torsions, abbreviated as MS-T(CD), but the program also supports the older MS-T(U) and MS-T(C) methods, the multi-structural local harmonic (MS-LH) approximation, and the multi- structural local quasiharmonic (MS-LQ) approximation. The MS-T methods account for the coupling of torsions to one another and to overall rotation and, to some extent, the coupling between torsions and other vibrational modes. By combining a redundant-internal-coordinate auto-generation procedure with torsional projection techniques, MSTor automates the identification of torsional vibrations and their separation from the other vibrational modes; this reduces the needed user input.

MSTor includes eight utility codes that can be used as stand-alone programs. One utility program calculates reduced moments of inertia by the method of Kilpatrick and Pitzer, one generates conformational structures, the third and fourth calculate volumes of torsional subdomains defined by Voronoi tessellation either analytically or by Monte Carlo sampling, the fifth and the sixth generates template input files, and the seventh calculates one-dimensional torsional partition functions using the torsional eigenvalue summation method. The final utility code is for computing dual level MS-T partition functions.

Licensing and downloading:

MSTor 2023 is licensed under the Apache License, Version 2.0.
The manual of MSTor 2023 is licensed under CC-BY-4.0.

Publications of results obtained with the MSTor 2023 software should cite the program and/or the article describing the program.

No guarantee is made that this software is bug-free or suitable for specific applications, and no liability is accepted for any limitations in the mathematical methods and algorithms used within. No consulting or maintenance services are guaranteed or implied.

The use of the MSTor 2023 implies acceptance of the terms of the licenses. MSTor 2023 can be downloaded here.

The MSTor MSTor 2023 will soon also be available through the Computer Physics Communications at http://www.cpc.cs.qub.ac.uk. It was submitted to the CPC Library on March 5, 2023.