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QCMP145. QCFF/PI - CFFTH2 (DOS Version of QCPE 593)
by A. K. Ponamaneni and T. G. Lenz, Department of Chemical Engineering, and A. K. Rappe and J. D. Vaughan, Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523 DOS Version of QCFF/PI-CFFTH This version includes an extension for the computation of S(T), Cp(T), (H(T)-H(O))/T and (G(T)-G(O))/T for organic compounds consisting of nitrogen and halogens and can accept as input the output files of various commercial graphics software. It includes the capability to treat heteroatomic molecules having carbon, hydrogen, oxygen, nitrogen and halogen atoms. Some of the subroutines have been modified so there is no need for the input of a symbolic formula. This version can run on an IBM-compatible AT 486 PC and can read the coordinate and connectivity information from the output of commercial graphics software. QCFF/PI This is the quantum mechanical extension of the consistent force field to PI-electron systems by A. Warshel and M. Levitt (revised version, 1973). QCFF/PI calculates equilibrium conformations and vibrational normal modes of ground and PI excited states of large conjugated molecules as well as the ground state of hydrocarbons (for which the potential parameters were available). The oscillator strength for PI transitions and I. R. intensities of the ground electronic state are calculated. Equilibrium geometries are calculated by the minimization of the molecular energy with the complete set of 3N Cartesian coordinates. The vibrational normal modes are then calculated by the diagonalization of the matrix of the second derivatives of the potential with respect to the mass-scaled Cartesian coordinates at the calculated minimum. The efficiency of the program is based on the availability of analytic first and second derivatives of the potential with respect to the Cartesian coordinates. For more information, see references 1-6 in the documentation. Features Added in QCFF/PI-CCFTHH (QCPE 593) The feature added in this version was a capability to compute the ideal gas entropy, the ideal gas heat capacity, the difference in the ideal gas enthalpy at the given temperature from its value at 0 degrees K and also the difference between the Gibbs free energy at a given temperature and its value at 0 degrees K. These thermodynamic quantities are obtained by use of the rigid rotor and harmonic oscillator models of statistical thermodynamics. Lines of Code: 8370 FORTRAN77 (MICROSOFT) |