[gmx-users] Units for electrical-field-x parameters

[Prithwish Nandi]

Okay, thanks.

It’s mentioned as :  
E
0
  = 2 V/nm, 

ω
 = 150/ps and 
t
0
 = 5 ps and 
σ
 = 1 ps

Omega : is this in cycles/ps , or, rad/ps ?

Not mentioned explicitly in manual. But, from source it seems to be in rad/ps.

Can anyone clarify, please?

Thanks,
P\\



> On 12 Feb 2019, at 13:38, Mark Abraham <mark.j.abraham at gmail.com> wrote:
> 
> Hi,
> 
> I think these are pretty well covered at
> http://manual.gromacs.org/documentation/current/reference-manual/special/electric-fields.html <http://manual.gromacs.org/documentation/current/reference-manual/special/electric-fields.html>
> and
> http://manual.gromacs.org/documentation/current/user-guide/mdp-options.html#electric-fields <http://manual.gromacs.org/documentation/current/user-guide/mdp-options.html#electric-fields>.
> Do let us know if there's anything missing, etc.
> 
> Mark
> 
> On Tue, 12 Feb 2019 at 11:23 Prithwish Nandi <prithwish.nandi at ichec.ie <mailto:prithwish.nandi at ichec.ie>>
> wrote:
> 
>> Hi,
>> What are the units of the four parameters for the electric-field-x,
>> electric-field-y, and electric-field-z parameters in Gromacs?
>> 
>> i.e. units for E0, omega, t0 and sigma ?
>> 
>> Let us discuss with an example, for example, an alternating field with
>> 0.2V/nm, 100 GHz. What would be the values and units of the above
>> parameters for this particular field?
>> 
>> Is E0 = Sqrt(2) * 0.2 V/nm ?  (i.e. r.m.s value?)
>>    t0 = 0
>>    Sigma = 0
>>    Omega  = 2*pi*nu = 2*pi*100 GHz =  2*pi/t = 2*pi/10 (rad/ps) = 0.628
>> rad/ps.  (t=1/nu = 1000/100 = 10 ps for nu = 100 GHz)
>> 
>> 
>> 
>> Is the above calculations correct?
>> 
>> Best,
>> PKN
>> 
>> 
>> 
>> Dr. Prithwish K Nandi, Ph.D.
>> Computational Scientist
>> Irish Centre for High-End Computing  (ICHEC) - www.ichec.ie
>> 7th Floor, The Tower, Trinity Technology & Enterprise Campus,
>> Grand Canal Quay, Dublin 2, Ireland
>> 
>> Tel: +353 1 5241608 ext. 22 <+353%201%20524%201608>
>> 
>> 
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