# [gmx-users] Time varying electric field - phase term

Johnny Lu johnny.lu128 at gmail.com
Thu Aug 28 14:43:25 CEST 2014

Or, can you wait a while before you turn on the field?

So far, I know that people can do npt after nvt.
Can you run simulation without field, then, with field?
Just have to count the delays.

There might be some truncation effect tough.... if you turn on the field
suddenly.

On Wed, Aug 27, 2014 at 3:25 PM, steven shawn <shawnsteven1 at gmail.com>
wrote:

> Thanks for your reply Johnny Lu. That is a very good point. But I have not
> seen any sin Electric field. Can gromacs generate sin Electric fields too?
>
>
> On Tue, Aug 26, 2014 at 8:33 PM, Johnny Lu <johnny.lu128 at gmail.com> wrote:
>
> > I wonder if gromacs can do both sine and cosine?
> >
> > If so, the sum angle formula can work.
> >
> >
> >
> http://en.wikipedia.org/wiki/List_of_trigonometric_identities#Angle_sum_and_difference_identities
> >
> >
> >
> > On Sat, Aug 23, 2014 at 10:42 AM, steven shawn <shawnsteven1 at gmail.com>
> > wrote:
> >
> > > Dear gromacs users, I am trying to use an electric field which is
> varying
> > > with time. I read the previous posts and successfully generated time
> > > varying electric field with E-xt, E-yt and E-zt.
> > >
> > > but I need an electric field which has an initial phase term (ie. of
> the
> > > form E= E0cos(2*pi*f*t+some angle term)) where i want to specify the
> > angle
> > > term. Most of the posts i read mentioned this angle term must be
> > specified
> > > in the third term after E-xt.
> > > I tried it but failed to generate an initial phase. Can anyone help me
> > with
> > > this?
> > >
> > >
> > > thanks in advance.
> > > --
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