$RAMAN group (relevant for all SCFTYPs) This input controls the computation of Raman intensity by the numerical differentiation produre of Komornicki and others. It is applicable to any wavefunction for which the analytic gradient is available, including some MP2 and CI cases. The calculation involves the computation of 19 nuclear gradients, one without applied electric fields, plus 18 no symmetry runs with electric fields applied in various directions. The numerical second differencing produces intensity values with 2-3 digits of accuracy. This run must follow an earlier RUNTYP=HESSIAN job, and the $GRAD and $HESS inputs from that first job must be given as input. If the $DIPDR is computed analytically by this Hessian job, it too may be read in, if not, the numerical Raman job will evaluate $DIPDR. Once the data from the 19 applied fields is available, the $ALPDR tensor is evaluated. Then the nuclear derivatives of the dipole moment and alpha polarizability will be combined with the normal coordinate information to produce the IR and Raman intensity of each mode. To study isotopic substitution speedily, provide $GRAD, $HESS, $DIPDR, and $ALPDR inputs, along with the desired atomic masses in $MASS. The code does not permit semi-empirical or solvation models to be used. EFIELD = applied electric field strength. The literature suggests values in the range 0.001 to 0.005. (default = 0.002 a.u.) ========================================================== ==========================================================

generated on 7/7/2017