For dynamic response properties (i.e., $\omega \ne 0$), various values of $\omega $ might be of interest, and it is considerably cheaper to compute properties for multiple values of $\omega $ in a single calculation than it is to run several calculations for one frequency each. The $fdpfreq input section is used to specify the frequencies of interest. The format is:
$fdpfreq property frequencies units $end
The first line is only required for third-order properties, to specify the flavor of first hyperpolarizability. The options are
StaticHyper (static hyperpolarizability)
SHG (second harmonic generation)
EOPockels (electro-optical Pockels effect)
OptRect (optical rectification)
The second line in the $fdpfreq section contains floating-point values representing the frequencies of interest. Alternatively, for dynamic polarizabilities an equidistant sequence of frequencies can be specified by the keyword WALK (see example below). The last line specifies the units of the input frequencies. Options are:
au (atomic units of frequency)
eV (frequency units, expressed in electron volts)
Hz (frequency units, expressed in Hertz)
nm (wavelength units, in nanometers)
cmInv (wavenumber units, ${\mathrm{cm}}^{-1}$)
$fdpfreq 0.0 0.03 0.05 au $end
$fdpfreq walk 0.00 0.10 0.01 au $end
$fdpfreq StaticHyper SHG EOPockels 1064 nm $end