Re: [gmx-users] constrained mdrun about linear rigid molecule ??

2012-01-12 Thread Mark Abraham

On 12/01/2012 8:40 PM, Kiwoong Kim wrote:

Hi,

I'm not good at handling Gromacs yet.

My question is about virtual interaction.

I'm doing simulation dealing with CO2 which is linear rigid molecule 
as you already know.

As pervasively known, I introduced virtual sites.

However, I don't know how to give initial coordinate correctly of 
dummy particles.


Let us consider following system.

x1-d1-x2

There are two real atom and one dummy particle between them with 
appropriate length ratio, a, from x1, and (1-a) from x2.
If I give the coordinates of three particles by the rules of above 
statement, i.e., dummy particle between them with appropriate length 
ratio, a, from x1, and (1-a) from x2..


Is it correct?


Looks fine.


Isn't there any unstable energy?


Why should there be?



Do I have to run any preceding run before equilibration run??
Otherwise, Is there any other way giving the correct coordinate of 
dummy particle ???


I expect you can give it any coordinates you like, and the interaction 
any value of a you like. Thereafter, it's in the hands of physics. If 
you want something reasonable, then probably choose the coordinates and 
the value of a in a consistent way.


Mark
--
gmx-users mailing listgmx-users@gromacs.org
http://lists.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at 
http://www.gromacs.org/Support/Mailing_Lists/Search before posting!
Please don't post (un)subscribe requests to the list. Use the 
www interface or send it to gmx-users-requ...@gromacs.org.

Can't post? Read http://www.gromacs.org/Support/Mailing_Lists


[gmx-users] constrained mdrun about linear rigid molecule ??

2012-01-12 Thread Kiwoong Kim
Hi,

I'm not good at handling Gromacs yet.

My question is about virtual interaction.

I'm doing simulation dealing with CO2 which is linear rigid molecule as you
already know.
As pervasively known, I introduced virtual sites.

However, I don't know how to give initial coordinate correctly of dummy
particles.

Let us consider following system.

x1-d1-x2

There are two real atom and one dummy particle between them with
appropriate length ratio, a, from x1, and (1-a) from x2.
If I give the coordinates of three particles by the rules of above
statement, i.e., dummy particle between them with appropriate length ratio,
a, from x1, and (1-a) from x2..

Is it correct? Isn't there any unstable energy?

Do I have to run any preceding run before equilibration run??
Otherwise, Is there any other way giving the correct coordinate of dummy
particle ???

Please help me..
-- 
gmx-users mailing listgmx-users@gromacs.org
http://lists.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at 
http://www.gromacs.org/Support/Mailing_Lists/Search before posting!
Please don't post (un)subscribe requests to the list. Use the 
www interface or send it to gmx-users-requ...@gromacs.org.
Can't post? Read http://www.gromacs.org/Support/Mailing_Lists