Re: want to modify NDSolve--molecular dynamics with mathematica
- To: mathgroup at smc.vnet.net
- Subject: [mg26365] Re: want to modify NDSolve--molecular dynamics with mathematica
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Wed, 13 Dec 2000 02:41:24 -0500 (EST)
- Organization: Universitaet Leipzig
- References: <90v82t$79m@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
you can write your equation with Mod[x[t],a0]
but it will make the InterpolatingFunction[]s
returned by NDSolve[] unusable. Because
x[t] will jump back to for x>a0 and the
interpolation is useless.
You must write your own initial value solver.
Regards
Jens
"Toshiyuki (Toshi) Meshii" wrote:
>
> Hello,
>
> I was wondering whether I can apply NDSolve to molecular dynamics, on the
> standpoint of periodical boundary condition.
>
> The eqation I want to solve is the simple Newton equation (Let me simplify
> the problem).
> m D[x, {x,2}] == F
> However, periodical boundary condition makes it difficult to apply NDSolve.
> That is, once
> 0<x[t]<a0
> is not satisfied (a0 is a constant), I have to move the atom so that this
> condition is satisfied.
> In concrete,
> if x[t]<0 ---> x[t]=x[t]+a0
> if x[t]>a0 ---> x[t]=x[t]-a0
> and then restart to solve the equation.
>
> Is there any way to realize this by directly applying NDSolve?
> If not, how can I modify NDSolve?
>
> -Toshi
- Follow-Ups:
- Re: Re: want to modify NDSolve--molecular dynamics with mathematica
- From: Richard Gass <gass@physics.uc.edu>
- Re: Re: want to modify NDSolve--molecular dynamics with mathematica