Section Linear Response
Some response properties can be calculated either via Sternheimer linear response or by using finite differences. You can use this variable to select how you want them to be calculated, it applies to em_resp and vib_modes calculation modes. By default, the Sternheimer linear-response technique is used.
The linear response is obtained by solving a self-consistent
Sternheimer equation for the variation of the orbitals. This
is the recommended method.
Properties are calculated as a finite-differences derivative of
the energy obtained by several ground-state calculations. This
method, slow and limited only to static response, is kept
mainly because it is simple and useful for testing purposes.
main/run.F90 : 99
call parse_variable(namespace, 'ResponseMethod', LR, get_resp_method)