Subject: Re: CCL:Geometry Optimization in a Uniform Electric Field

From: "Phillip D. Matz" <[email-masked]>
Date: Mon, 27 Nov 2000 09:28:30 -0800

Hello Yubo Fan!

Attached is my original reply to Zhongfang Chen when he asked a similar
question back in September 2000.

To optimize in a uniform electric field you would use the OPT keyword and
the FIELD keyword, you have only to decide the magnitude of the field by
using a switch.  An example:

#P RHF/STO-3G OPT Field=(Z+1000) pop=reg

The keyword you are looking for is Field.  I like to use this keyword when
optimizing geometries in an electric dipole field when modeling molecular
interactions in IMS (ion mobility spectrometry).  For me the use of the
keyword simply involves placing the
keyword

Field = Z + 1000

into to route line of an optimization job, or any job for that matter.  My
example choice of 1000 simply means Gaussian is applying an electric dipole
field in the Z direction of 0.1 a.u.  This is of course a rather large field
but it is just an example.  Look at the Gaussian manual for your options
with field, here is a clip though:

 - from Gaussian manual
....the field can either involve electric multipoles (through hexadecapoles)
or a Fermi-contact term. Field requires a parameter in one of these two
formats:

 M±N    or    F(M)N

where M designates a multipole, and F(M) designates a Fermi contact
perturbation for atom M (following the ordering in the molecule
specification section of the input file).  N*0.0001 specifies the magnitude
of the field in atomic units in the first format, and
specifies the magnitude of the Fermi contact perturbation in the second
format.
 - from Gaussian manual

Respectfully,
Phillip Matz
[email-masked]

----- Original Message -----
From: "Yubo Fan" <[email-masked]>
To: <[email-masked]>
Sent: Thursday, November 23, 2000 6:43 AM
Subject: CCL:Geometry Optimization in a Uniform Electric Field

> Hi,
>
> We are studying behaviors and properties of molecules in uniform
> electric fields in these weeks. I know G98 can be used to calculate the
> interaction between point charge and molecules by using option massage.
> Is it possible that geometries of various molecules in a uniform
> electric field can be optimized by G98?
>
> Thanks in advance
>
> Y. Fan
>
> --
> =============================================================
> Yubo Fan                         Email: [email-masked]
> Organic Synthesis Lab
> The Department of Chemistry
> Fudan University                 Phone: 8621-65648139
> No. 220 Handan Road              Fax:   8621-65641740
> Shanghai, 200433
> P. R. China
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