16.2 evib features
The evib module, implemented in TURBOMOLE, allows to calculate the matrix elements of the first order derivative of the Kohn-Sham operator with respect to atomic displacements \(\chi\) \[\begin{equation}
{H^{e}_{\mu\nu,\chi}}=\bigl\langle\mu\bigl|\dfrac{\mbox{d}\hat{H}^{\text{e}}_1}{\mbox{d}\chi}\bigr|\nu\bigr\rangle,
\end{equation}\](16.4) which are required to obtain the first order EV coupling constant, as given in Eq. (16.3) [317].
Limitations:
only c1 symmetry at the moment,
RI-approximation only partely implemented.