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

[Erik Marklund]

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.

/Erik
> 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