The calculation of frequency-dependent (hyper)polarizabilities and related properties (Raman, ORD) is activated with the block key RESPONSE
RESPONSE
END
In this example only the zz component of the dipole polarizability tensor is calculated, at zero
frequency. The orientation of the molecule is therefore crucial. Be aware that
the program may modify the orientation of the molecule if the input coordinates
do not agree with the symmetry conventions in ADF!
(This calculation could equivalently be done through a finite field method).
See also the alternative implementation with the AORESPONSE key that offers some unique features like magnetizability, and lifetime options.
The impact of various approximations on the quality of computed polarizabilities has been studied in, for instance, Refs. [74,82,89]. If you are new to this application field, we strongly recommend that you study a few general references first, in particular when you consider hyperpolarizability calculations. These have many pitfalls, technically (which basis sets to use, application of the DEPENDENCY key) and theoretically (how do theoretical tensor components relate to experimental quantities, different conventions used). Please, take a good look both at ADF-specific references [75-77,90] and at general references related to this subject: Refs. [91-93], the entire issues of Chem.Rev.94, the ACS Symposium Series #628, and further references in the ADF-specific references.
RESPONSE
ALLCOMPONENTS
Nfreq Nfreq
FrqBeg FirstFreq
FrqEnd LastFreq
[Optional Frequency/Energy Unit]
ALLTENSOR
Quadrupole
Octupole
END
Entire tensor or only one component
You specify the ALLCOMPONENTS subkey to get the entire polarizability tensor, instead of just the zz component.
Frequencies or wavelengths
Instead of performing the calculation at zero frequency (which results in the static polarizability), one can specify an even-spaced sequence of frequencies, using the subkeys Nfreq, FrqBeg, and FrqEnd with obvious meaning. The (first and last) frequency values are by default in eV. This can be changed into Hartree units (a.u.) or in wavelengths (angstroms) by typing HARTREE or ANGSTROM on a separate line within the RESPONSE block, instead of [Optional Frequency/Energy Unit].
Higher multipole polarizabilities
Instead of just calculating the dipole-dipole polarizability, one may address the dipole-quadrupole, quadrupole-quadrupole, dipole-octupole, quadrupole-octupole, and octupole-octupole polarizability tensors. These can all be calculated in a single run, using the subkey ALLTENSOR. If only quadrupole-quadrupole or octupole-octupole tensors are needed, the subkey quadrupole or octupole should be used.
Accuracy and convergence, RESPONSE key
