Improved interface SNF (vibrational spectra) to ADF

SNF has been developed for the quantum chemical calculation of vibrational spectra. SNF is maintained in the group of Prof. Reiher at ETH Zurich. Recently there has been an update of the SNF program, which contains an improved interface to ADF.

With the SNF program infrared, Raman, and VROA spectra can be obtained using the harmonic approximation for the frequencies and the double harmonic approximation for the intensities. Vibrational frequencies are determined using numerical differentiation of analytical gradients of the total electronic energy, while infrared, Raman, and VROA intensities are obtained by numerical differentiation of dipole moments and (generalized) polarizability tensor components with respect to nuclear coordinates. Note that the calculation of VROA intensities is not (yet) interfaced to ADF.

A selective calculation of normal modes is possible with a so-called mode-tracking algorithm that is implemented in the AKIRA program, which has been interfaced to ADF.