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[Licence| Download | New Version Template] aemf_v1_0.tar.gz(2747 Kbytes)
Manuscript Title: MSTor: A program for calculating partition functions, free energies, enthalpies, entropies, and heat capacities of complex molecules including torsional anharmonicity
Authors: Jingjing Zheng, Steven L. Mielke, Kenneth L. Clarkson, Donald G. Truhlar
Program title: MSTor
Catalogue identifier: AEMF_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 183(2012)1803
Programming language: Fortran 90, C, and perl.
Computer: Itasca (HP Linux cluster, each node has two-socket, quad-core 2.8 GHz Intel Xeon X5560 "Nehalem EP" processors), Calhoun (SGI Altix XE 1300 cluster, each node containing two quad-core 2.66 GHz Intel Xeon "Clovertown"-class processors sharing 16 GB of main memory), Koronis (Altix UV 1000 server with 190 6-core Intel Xeon X7542 "Westmere" processors at 2.66 GHz), Elmo (Sun Fire X4600 Linux cluster with AMD Opteron cores), and Mac Pro (two 2.8GHz Quad-core intel Xeon processors).
Operating system: Linux/Unix/Mac OS.
RAM: 2 Mbytes
Keywords: Enthalpy, Entropy, Free energy, Heat capacity, Internal rotation, Molecular torsions, Partition functions, Statistical mechanics, Vibrational anharmonicity.
Classification: 16.3, 16.12, 23.

Nature of problem:
Calculation of the partition functions and thermodynamic functions (standard-state energy, enthalpy, entropy, and free energy as functions of temperatures) of complex molecules involving multiple torsional motions.

Solution method:
The multi-structural approximation with torsional anharmonicity (MS-T). The program also provides results for the multi-structural local harmonic approximation. [1]

There is no limit on the number of torsions that can be included in either the Voronoi calculation or the full MS-T calculation. In practice, the range of problems that can be addressed with the present method consists of all multi-torsional problems for which one can afford to calculate all the conformations and their frequencies.

Unusual features:
The method can be applied to transition states as well as stable molecules. The program package also includes the hull program for the calculation of Voronoi volumes and five utility codes that can be used as stand-alone programs to calculate reduced moment-of-inertia matrices by the method of Kilpatrick and Pitzer, to generate conformational structures, to calculate, either analytically or by Monte Carlo sampling, volumes for torsional subdomain defined by Voronoi tessellation of the conformational subspace, to generate template input files, and to calculate one-dimensional torsional partition functions using the torsional eigenvalue summation method.

Additional comments:
The program package includes a manual, installation script, and input and output files for a test suite.

Running time:
There are 24 test runs. The running time of the test runs on a single processor of the Itasca computer is less than 2 seconds.

[1] Practical Methods for Including Torsional Anharmonicity in Thermochemical Calculations of Complex Molecules: The Internal-Coordinate Multi-structural Approximation, J. Zheng, T. Yu, E. Papajak, I, M. Alecu, S. L. Mielke, and D.G. Truhlar, Physical Chemistry Chemical Physics 13 (2011) 10885-10907.