Static and frequency dependent polarizabilities

 

Frequency dependent polarizabilities  is calculated from a set of linear response  functions as described in Ref. [28]. In ABACUS  the calculation of frequency-dependent linear response functions is requested through the keyword .ABALNR   in the general input module. An input file requesting the calculation of the frequency dependent polarizability of a molecule may then be calculated using the following input:

**DALTON INPUT
.RUN PROPERTIES
*END OF GENERAL
**WAVE FUNCTIONS
.HF
**PROPERTIES
.ABALNR
*ABALNR
.ALFA
.FREQUE
    2
0.0 0.09321471
*END OF INPUT

We no The *ABALNR   input section controls the calculation of the frequency dependent linear response function , and we have requested the calculation of frequency dependent polarizabilities  through the keyword .ALFA  . Furthermore, we must specify at what frequencies the polarizability is to be calculated. This is done with the keyword .FREQUE  , and in this run the polarizability is to be evaluated at zero frequency (corresponding to the static polarizability) and at a frequency (in atomic units) corresponding to a incident laser beam of wavelength 488.8 nm.

There is also another way of calculating the static polarizability, and this is by using the keyword .POLARI   in the **PROPERTIES   input modules. Thus, if we only want to evaluate the static polarizability of a molecule, this may be achieved by the following input:

**DALTON INPUT
.RUN PROPERTIES
**WAVE FUNCTIONS
.HF
**PROPERITES
.POLARI
*END OF INPUT

Furthermore, the general RESPONSE program will also calculate the frequency-dependent polarizability   as minus the linear response functions through the input

**DALTON INPUT
.RUN RESPONSE
**WAVE FUNCTIONS
.HF
**RESPONSE
*LINEAR
.DIPLEN
*END OF INPUT

For further details about input for the response program, we refer to Chapter .