#! /bin/sh # FOCDFT is used to calculate exciton transfer integrals # for the ethylene dimer and trimer using CIS (HartreeFock with TDA). # First the isolated fragments are calculated. # Because in the final complexes the 2 or 3 ethylene molecules are the same, # only one fragment needs to be calculated. # For such a small molecule, a relatively small TZP basis set is used, which is # not sufficient for excitations to Rydberg-like orbitals. # For larger molecules a TZ2P basis set is in most cases # sufficient. In that case one might even consider smaller basis sets. # In a real application one also probably wants to calculate a higher number # of excitations than that are calculated in this example. # Next the choice of XC functional is important. # If FOCDFT is used for the calculation of exciton transfer # best is to use an XC functional that can reasonably well # calculate both local excitations as well as charge-transfer excitations, # like long range-separated functionals. # For analysis reasons we also do a CIS calculation # on the ethylene fragment. # In the calculation D(2h) symmetry is used. # The B1.u excitation will be a valence excitation, and # the B3.u excitation will be a Rydberg excitation. # Note that in D(2h) symmetry the orientation of the molecule # matters in what is called a B1.u or B3.u excitation, for example. AMS_JOBNAME=Frag $AMSBIN/ams <