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593.QCFF/PI-CFFTH: QCFF/PI Including Extension for the
Computation of S°(T), CO(p,°)(T), [H°(T)-H°(0)]/T
and
[G°(T)-G°(0)]/T
by S. Ramachandran and T. G. Lenz, Department of Chemical Engineering, and J. D. Vaughan and A. K. Rappé, Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523 QCPE 593 is an extension of QCPE 534 by D. Bugay and W. Leenstra after QCPE 247 by A. Warshel and M. Levitt. This program calculates equilibrium conformations and vibrational normal modes of ground and PI excited states of large conjugated molecules as well as of the ground state of any other molecule for which the potential parameters are available. The oscillator strengths of PI transitions and the IR intensities of the ground electronic state are also calculated. Equilibrium geometries are calculated by minimization of the molecular energy with respect to the complete set of 3N Cartesian coordinates. The vibrational normal modes are then calculated by diagonalization of the matrix of 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 analytical first and second derivatives of the potential with respect to the Cartesian coordinates. New features incorporated in this version are the computation of the ideal gas entropy, the ideal gas heat capacity, the difference of the enthalpy of the ideal gas at a given temperature from its value at 0°K. These thermodynamic quantities are obtained by use of the rigid rotor and harmonic oscillator models of statistical thermodynamics. For references in addition to QCPE programs 247 and 534, see: A. Warshel and M. Karplus, J. Am. Chem. Soc., 94, 5613 (1974); S. Lifson and A. Warshel, J. Chem. Phys., 49, 5116 (1968); T. Lenz and J. Vaughan, J. Comp. Chem., 11, 351 (1990). FORTRAN 77 (IRIS 4D20-GT; Standard UNIX F-77; VAX-VMS) Lines of Code: 5907 |