From: Axel Kohlmeyer (
Date: Mon Nov 17 2008 - 14:31:02 CST

On Mon, 17 Nov 2008, wrote:

???> Hi,

dear shuai,
???> I have a general question regarding the memory use of VMD here.
???> In windows, is VMD capable of using the virtual memory or is it capable of
???> storing large data file temporarily in harddisk? I am using VMD for the
???> visualization of large configurations (200000 atoms in each frame, usually
???> more than 500 frames in total) and I just have 4GB RAM on my desktop, so it
???> would be a bad news for me if VMD can't use virtual memory.

john can probably comment on this in more detail, but the windows
builds of VMD traditionally always had some limitations due to the
limitations of windows or problems of compiling required support
libraries in 64-bit mode. there are plans to make handling of very
large systems more efficient.

if it is so important to be able to fully use all available
memory, it is probably best to install linux instead (you
can have a dual-boot machine, btw), or think about ways to
reduce the memory requirements of your visualizations.

i've been working on visualizations of very large systems
and very rarely all atoms were needed. so i used to have
a two step process of first removing parts that were required
for the simulation, but didn't matter for visualization
and thus cut down the need for memory. processing scripts
using bigdcd are a great help for that.

a second option is to create visualizations and then render
them to movies. i've been using this predominantly, when
my graphics hardware was not powerful enough to handle very
large systems fast enough. this can also be done in batch
mode with some simple scripts...


???> Thanks,
???> Shuai

Axel Kohlmeyer
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
If you make something idiot-proof, the universe creates a better idiot.