Example: Vibrational Circular Dichroism (VCD): NHDT¶
Analytical frequencies with subsequent calculation of vibrational circular dichroism (VCD)
The VCD keyword can be used to calculate VCD spectra. It is important to note that the VCD keyword only works in combination with the keys AnalyticalFreq and symmetry NOSYM.
Recommended is use to use high accuracy for the geometry optimization which one needs to do before the frequency calculation. This simple example is an NHDT molecule, which is NH3 where one hydrogen atom is replaced with deuterium and another with tritium.
Note that the fragment t21 names, like t21.N, are made by the adf script, and here this knowledge is used.
$ADFBIN/adf <<eor Atoms N 0.000000 0.000000 0.010272 H -0.471582 -0.816803 0.407861 H.D 0.943163 0.000000 0.407861 H.T -0.471582 0.816803 0.407861 End AtomProps H.D m=2.014101778 H.T m=3.01604927 End Basis Type TZP Core None End Symmetry NOSYM xc GGA BP86 end Fragments N t21.N H t21.H H.D t21.D H.T t21.T End BeckeGrid quality verygood End AnalyticalFreq End VCD end input eor