[gmx-users] programmes to have in double precision besides mdrun_d

Erik Marklund erikm at xray.bmc.uu.se
Wed Jun 17 15:17:53 CEST 2009

Jussi Lehtola skrev:
> On Wed, 2009-06-17 at 13:45 +0200, Berk Hess wrote:
>> Hi,
>> Nothing needs to be double precision.
>> Why do you want mdrun in double precision?
>> The only common reason for this is normal mode analysis,
>> in which case you need all the tools involved in double precision.
>> For normal MD simulation there is nearly never a need for
>> double precision.
> If you want to run accurate NVE simulations, double precision is
> important. If you use thermostats, then there is no need for double
> precision.
I can testify to that. Without double precision I've had problems with 
drifting total energy when doing non-periodic NVE.

> Also, I have found that double precision can be nice for energy
> minimization since it can handle more pathological cases than single
> precision. Still, usually it doesn't matter much whether the starting
> point was prepared in single or double precision.

Erik Marklund, PhD student
Laboratory of Molecular Biophysics,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,    75124 Uppsala, Sweden
phone:    +46 18 471 4537        fax: +46 18 511 755
erikm at xray.bmc.uu.se    http://xray.bmc.uu.se/molbiophys

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