[gmx-users] Black whole simluations

David van der Spoel spoel at xray.bmc.uu.se
Fri Mar 14 16:55:48 CET 2008

Mark Abraham wrote:
> roger han wrote:
>> Dear mister gromacs
>> My professor interested in black wholes. How can I put a particle in a box and set mass to infinity? Which solvent is best choice and could there be problems with pressure? I'm also not sure about periodic boundaries. Could two black wholes see each other if box too small? 
> You can't do molecular dynamics on particles of infinite mass. Whether
> it would be sensible to be able to simulate any kind of dynamics on such
> a particle is a debate best held on a cosmology mailing list :-)

GROMACS is definitely not the best choice for this. However, if you 
supply a user-potential you can simulate gravity, by disguising it as an 
always attractive Coulomb potential. You will have to store the mas in 
the charge field as well as in the mass field. Then you're good to go. 
Obviously no black hole has infinite mass, so there is not a problem there.

Your simulation will be purely classical, as stated by the previous 
posters. Please prepare some input for the Solar system and post it on 
the gromacs website. I'm sure you can make animations using e.g. pymol 
of your gravitational simulations.

> Mark
> P.S. I checked the date. April 1 is 16 days away!
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David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://folding.bmc.uu.se

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