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

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 multistructural approximation with torsional anharmonicity (MS-T). The MS-T approximation accounts for the coupling of torsions to one another and to overall rotation and, to some extent, the coupling between torsions and other vibrational modes. The program also calculates partition functions and thermodynamic functions by the multi-structural local harmonic (MS-LH) approximation or multi-structural local quasiharmonic (MS-LQ) approximation. This program package also includes seven 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.