# CCL:G: Magnitude of static field used for calculation of polarizability

*From*: Susi Lehtola <susi.lehtola|a|alumni.helsinki.fi>
*Subject*: CCL:G: Magnitude of static field used for calculation of
polarizability
*Date*: Wed, 25 Apr 2018 19:06:39 +0300

Sent to CCL by: Susi Lehtola [susi.lehtola^^alumni.helsinki.fi]
On 04/25/2018 04:22 PM, Suresh Kumar Venkata Neelamraju
nvs.kumar^^iiit.ac.in wrote:

Sent to CCL by: "Suresh Kumar Venkata Neelamraju"
[nvs.kumar%x%iiit.ac.in] Dear members of CCL,
Can anyone please inform the magnitude of static field used by
Gaussian09 for calculation of static polarizability.

`One does not need a field to calculate static polarizability. It can
be
``solved at zero field as the second derivative of the molecular energy
``using a response formalism. This appears to be the approach used in
``Gaussian.
`

`If you do not have a program that supports this approach, you can
always
``estimate the static polarizability by finite differences. (A static
``field is very easy to implement, as it only requires dipole integrals.)
``You can then run calculations at several values of the field (as well
as
``all field directions), and estimate the polarizability using e.g. a
``three- or five-point stencil.
` --
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Mr. Susi Lehtola, PhD Junior Fellow, Adjunct Professor
susi.lehtola-$-alumni.helsinki.fi University of Helsinki
http://www.helsinki.fi/~jzlehtol Finland
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Susi Lehtola, dosentti, FT tutkijatohtori
susi.lehtola-$-alumni.helsinki.fi Helsingin yliopisto
http://www.helsinki.fi/~jzlehtol
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