$TDHF

$TDHF group (relevant for SCFTYP=RHF if RUNTYP=TDHF)

This group permits the analytic calculation of various static and/or frequency dependent polarizabilities, with an emphasis on important NLO properties such as second and third harmonic generation. The method is programmed only for closed shell wavefunctions, at the semi-empirical or ab initio level. Ab initio calculations may be direct SCF, or parallel, if desired.

Because the Fock matrices computed during the time- dependent Hartree-Fock CPHF are not symmetric, you may not use symmetry. You must enter NOSYM=1 in $CONTRL!

For a more general numerical approach to the static properties, see $FFCALC.

NFREQ
= Number of frequencies to be used. (default=1)

FREQ
= An array of energy values in atomic units. For example: if NFREQ=3 then FREQ(1)=0.0,0.1,0.25. By default, only the static polarizabilities are computed. (default is freq(1)=0.0)

The conversion factor from Hartree to wave numbers is 219,474.6, and the wavelength is given (in nm) by 45.56/FREQ.

MAXITA
= Maximum number of iterations for an alpha computation. (default=100)

MAXITU
= Maximum number of iterations in the second order correction calculation. This applies to iterative beta values and all gammas. (default=100)

ATOL
= Tolerance for convergence of first-order results. (default=1.0d-05)

ATOL
= Tolerance for convergence of second-order results. (default=1.0d-05)

RETDHF
= a flag to choose starting points for iterative calculations from best previous results. (default=.true.)

* * * the following NLO properties are available * * *

BSHG
= Calculate beta for second harmonic generation.

BEOPE
= Calculate beta for electrooptic Pockels effect.

BOR
= Calculate beta for optical rectification.

GTHG
= Calculate gamma for third harmonic generation.

GEFISH
= Calculate gamma for electric-field induced second harmonic generation.

GIDRI
= Calculate gamma for intensity dependent refractive index.

GOKE
= Calculate gamma for optical Kerr effect.

These will be computed only if a nonzero energy is requested. The default for each flag is .TRUE., and they may be turned off individually by setting some .FALSE. Note however that the program determines the best way to calculate them. For example, if you wish to have the SHG results but no gamma results are needed, the SHG beta will be computed in a non-iterative way from alpha(w) and alpha(2w). However if you request the computation of the THG gamma, the second order U(w,w) results are needed and an iterative SHG calculation will be performed whether you request it or not, as it is a required intermediate.

Reference:
S.P.Karna, M.Dupuis J.Comput.Chem. 12, 487-504 (1991).
P.Korambath, H.A.Kurtz, in "Nonlinear Optical Materials", ACS Symposium Series 628, S.P.Karna and A.T.Yeates, Eds. pp 133-144, Washington DC, 1996.

Review: D.P.Shelton, J.E.Rice, Chem.Rev. 94, 3-29(1994).


Back to list of input groups...