$FORCE group (optional, relevant for RUNTYP=HESSIAN,OPTIMIZE,SADPOINT) This group controls the computation of the hessian matrix (the energy second derivative tensor, also known as the force constant matrix), and an optional harmonic vibrational analysis. This can be a very time consuming calculation. However, given the force constant matrix, the vibrational analysis for an isotopically substituted molecule is very cheap. Related input is HESS= in $STATPT, and the $MASS, $HESS, $GRAD, $DIPDR, $VIB inputs. Calculation of the hessian automatically yields the dipole derivative tensor, giving IR frequencies. Raman intensities are obtained by following with RUNTYP=RAMAN. METHOD = chooses the computational method: = ANALYTIC is a fully analytic calculation. This is implemented for SCFTYP=RHF, UHF, ROHF, GVB (for NPAIR=0 or 1, only), and MCSCF (for CISTEP=ALDET or ORMAS, only). R-DFT and U-DFT are also analytic. This is the default for these cases. = SEMINUM does numerical differentiation of analytically computed first derivatives. This is the default for UHF, MCSCF using other CISTEPs, all solvent models, relativistic corrections, and most MP2 or CI runs. = FULLNUM numerically differentiates the energy twice, which can be used by all other cases. It requires many energies (a check run will tell how many) and so it is mainly useful for systems with only very few symmetry unique atoms. The default for METHOD is to pick ANALYTIC over SEMINUM if that is programmed, and SEMINUM otherwise. FULLNUM will never be chosen unless you specifically request it. RDHESS = a flag to read the hessian from a $HESS input, rather than computing it. This variable pertains only to RUNTYP=HESSIAN. See also HESS= in the $STATPT input group. (default is .FALSE.) PURIFY = controls cleanup Given a $ZMAT, the hessian and dipole derivative tensor can be "purified" by transforming from Cartesians to internals and back to Cartesians. This effectively zeros the frequencies of the translation and rotation "modes", along with their IR intensities. The purified quantities are punched out. Purification does change the Hessian slightly, frequencies at a stationary point can change by a wave number or so. The change is bigger at non-stationary points. (default=.FALSE. if $ZMAT is given) PRTIFC = prints the internal coordinate force constants. You MUST have provided $ZMAT input to use this. (Default=.FALSE.) --- the next four apply to numeric differentiation ---- NVIB = The number of displacements in each Cartesian direction for force field computation. This pertains only to METHOD=SEMINUM, as FULLNUM always uses double difference formulae. = 1 Move one VIBSIZ unit in each positive Cartesian direction. This requires 3N+1 evaluations of the wavefunction, energy, and gradient, where N is the number of SYMMETRY UNIQUE atoms given in $DATA. = 2 Move one VIBSIZ unit in the positive direction and one VIBSIZ unit in the negative direction. This requires 6N+1 evaluations of the wavefunction and gradient, and gives a small improvement in accuracy. In particular, the frequencies will change from NVIB=1 results by no more than 10-100 wavenumbers, and usually much less. However, the normal modes will be more nearly symmetry adapted, and the residual rotational and translational "frequencies" will be much closer to zero. (default) VIBSIZ = Displacement size (in Bohrs). This pertains to Both SEMINUM and FULLNUM. Default=0.01 Let 0 mean the Vib0 geometry, and D mean all the displaced geometries NPRT = 1 Print orbitals at 0 and D = 0 Print orbitals at 0 only (default) NPUN = 2 Punch all orbitals at 0 and D = 1 Punch all orbitals at 0 and occupied orbs at D = 0 Punch all orbitals at 0 only (default) ----- the rest control normal coordinate analysis ---- VIBANL = flag to activate vibrational analysis. (the default is .TRUE. for RUNTYP=HESSIAN, and otherwise is .FALSE.) SCLFAC = scale factor for vibrational frequencies, used in calculating the zero point vibrational energy. Some workers correct for the usual overestimate in SCF frequencies by a factor 0.89. ZPE or other methods might employ other factors, see J.P.Merrick, D.Moran, L.Radom J.Phys.Chem.A 111, 11683-11700 (2007). The output always prints unscaled frequencies, so this value is used only during the thermochemical analysis. (Default is 1.0) TEMP = an array of up to ten temperatures at which the thermochemistry should be printed out. The default is a single temperature, 298.15 K. To use absolute zero, input 0.001 degrees. FREQ = an array of vibrational frequencies. If the frequencies are given here, the hessian matrix is not computed or read. You enter any imaginary frequencies as negative numbers, omit the zero frequencies corresponding to translation and rotation, and enter all true vibrational frequencies. Thermodynamic properties will be printed, nothing else is done by the run. PRTSCN = flag to print contribution of each vibrational mode to the entropy. (Default is .FALSE.) DECOMP = activates internal coordinate analysis. Vibrational frequencies will be decomposed into "intrinsic frequencies", by the method of J.A.Boatz and M.S.Gordon, J.Phys.Chem., 93, 1819-1826(1989). If set .TRUE., the $ZMAT input may define more than 3N-6 (3N-5) coordinates. (default=.FALSE.) PROJCT = controls the projection of the hessian matrix. The projection technique is described by W.H.Miller, N.C.Handy, J.E.Adams in J. Chem. Phys. 1980, 72, 99-112. At stationary points, the projection simply eliminates rotational and translational contaminants. At points with non-zero gradients, the projection also ensures that one of the vibrational modes will point along the gradient, so that there are a total of 7 zero frequencies. The other 3N-7 modes are constrained to be orthogonal to the gradient. Because the projection has such a large effect on the hessian, the hessian is punched both before and after projection. For the same reason, the default is .FALSE. to skip the projection, which is mainly of interest in dynamical calculations. ========================================================== There is a program ISOEFF for the calculation of kinetic and equilibrium isotope effects from the group of Piotr Paneth at the Technical University of Lodz. This program will accepts data computed by GAMESS (and other programs), and can be requested from paneth@p.lodz.pl ==========================================================

generated on 7/7/2017