correcting my typo: if you set tempi>0 (not temp0>0) then the seed should
affect the velocity assignment.
On Fri, Feb 4, 2022 at 12:11 PM Carlos Simmerling <
carlos.simmerling.gmail.com> wrote:
> ntt=1 doesn't use the random number generator, so won't be affected by the
> seed (ntt=3 is). if you set temp0>0, then the seed should affect the
> initial velocity assignment.
>
> On Fri, Feb 4, 2022 at 12:01 PM Dr. Anselm Horn <anselm.horn.fau.de>
> wrote:
>
>> Dear Carlos,
>>
>> I did not read in any velocities, since I used a structure from a
>> minimization. The thermostat was NTT=1.
>>
>> Do I miss something?
>>
>> Best regards,
>>
>> Anselm
>>
>>
>> Am 04.02.2022 um 16:00 schrieb Carlos Simmerling:
>> > which thermostat did you use? also, did you read velocities from the
>> input
>> > coordinates? these are two places that can be affected by the seed.
>> >
>> > On Fri, Feb 4, 2022 at 9:09 AM Dr. Anselm Horn <anselm.horn.fau.de>
>> wrote:
>> >
>> >> Dear Amber experts,
>> >>
>> >> I have a short question regarding the random number generator for
>> >> initial velocities (TEMPi) on GPUs:
>> >>
>> >> I ran two MD simulations in a periodic solvent box starting from a
>> >> minimized structure, with weak-temperature coupling (NTT=1) and an
>> >> initial temperature of 50 K (TEMPi=50.0); for each simulation, I used
>> >> an explicit, but different random number seed (ig=NNN). I used the
>> >> executable pmemd.cuda_DPFP (Amber20, patch12) on a A40-GPU, since my
>> >> original intention was to test whether system relaxation might be save
>> >> on GPUs.
>> >>
>> >> The resulting trajectories of the two runs, however, were identical,
>> >> although different random seeds were used.
>> >>
>> >> Is the ig-seed not used on GPUs, or for NTT=1 in general?
>> >>
>> >> Maybe I misunderstood the section 21.6.7 in the Amber manual about
>> >> temperature regulation...
>> >> I did not check ig=-1 up to now, though.
>> >>
>> >> Best regards,
>> >>
>> >> Anselm
>> >>
>> >> Bioinformatik | NHR.FAU
>> >> Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)
>> >> Germany
>> >>
>> >>
>> >>
>> >>
>> >>
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Received on Fri Feb 04 2022 - 09:30:05 PST
