11.12 Linear-Scaling Computation of Electric Properties

11.12.1 $fdpfreq Input Section

For dynamic response properties (i.e., ω0), various values of ω might be of interest, and it is considerably cheaper to compute properties for multiple values of ω 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, cm-1)

Example 11.19  Static and dynamic polarizabilities, atomic units:

$fdpfreq
   0.0 0.03 0.05
   au
$end

Example 11.20  Series of dynamic polarizabilities, starting with 0.00 incremented by 0.01 up to 0.10:

$fdpfreq
   walk 0.00 0.10 0.01
   au
$end

Example 11.21  Static first hyperpolarizability, second harmonic generation and electro-optical Pockels effect, wavelength in nm:

$fdpfreq
   StaticHyper SHG EOPockels
   1064
   nm
$end