VMD-L Mailing List

From: Bogdan Costescu (bogdan.costescu_at_iwr.uni-heidelberg.de)
Date: Wed Mar 17 2004 - 13:05:14 CST

On Wed, 17 Mar 2004, John Stone wrote:

> I've heard from someone else about a recent 64-bit build of Charmm
> producing DCD files that VMD/CatDCD can't read

The problem with the 64-bit build of CHARMM is that the binary files
have headers loosely specified with only "INTEGER", which is 32 bit on
a 32 bit machine and 64 bit on a 64 bit machine. So the header values
get shifted and the programs that relied on them being at certain
offsets don't function anymore. That is true also for a 32 bit versus
a 64 bit version of CHARMM itself.

I haven't looked at other programs (neither simulation ones like NAMD
not visualisation ones like VMD) to see how these values are defined
there. If they are also loosely defined, their 64 bit versions should
be able to deal with binary files created by CHARMM and viceversa.

On the contrary, atom coordinates are strictly defined as "REAL*4" so
their size is the same on both types of platforms. 

-- 
Bogdan Costescu
IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: Bogdan.Costescu_at_IWR.Uni-Heidelberg.De