RESPONSE
ALLCOMPONENTS
VANDERWAALS NVanderWaals
{ALLTENSOR}
END
Simple dispersion coefficients (the dipole-dipole interaction
between two identical molecules, the C6 coefficient) are calculated
in a single ADF calculation. General dispersion coefficients are obtained with
the auxiliary program DISPER, which uses two output files (file named TENSOR)
of two separate ADF runs as input. See the Properties and the Examples documents.
To get the dispersion coefficients one has to calculate polarizabilities at
imaginary frequencies between 0 and infinity. The ADF program chooses the
frequencies itself. The user has to specify the number of frequencies, which in
a sense defines the level of accuracy, as an argument to the subkey VanDerWaals.
NVanderWaals
One can specify the number of frequencies with NVanderWaals. Ten frequencies is reasonable. Without the key ALLTENSOR only dipole-dipole interactions are considered. If ALLTENSOR is specified, higher dispersion coefficients are also calculated. This ADF calculation generates a file with name TENSOR, which contains the results of multipole polarizabilities at imaginary frequencies. This TENSOR file has to be saved. Similarly, the TENSOR file for the second monomer has to be saved. The files have to be renamed to files 'tensorA' and 'tensorB' (case sensitive) respectively. Then the program DISPER has to be called in the same directory where the 'tensorA' and 'tensorB' files are located. DISPER needs no further input. See the Properties document.
