[gmx-users] Temperature Annealing

abdus sabuj sabujbuetche at gmail.com
Mon Jan 25 20:41:11 CET 2016


Hi Justin,

Here is the mdp file I used for NPT equilibration...


integrator               = md
nsteps                   = 10000000
dt                                   = 0.001
nstenergy                = 1000
nstxout                  = 1000
nstvout                  = 1000





vdw-type                 = cut-off


continuation    = yes                ; first dynamics run
constraint_algorithm = lincs    ; holonomic constraints
constraints     = all-bonds             ; all bonds (even heavy atom-H
bonds) constrained
;lincs_iter      = 1                         ; accuracy of LINCS
;lincs_order     = 4                         ; also related to accuracy
lincs-warnangle = 90                    ; warning after rotating the bond


ns_type         = grid          ; search neighboring grid cels
nstlist         = 10                 ; 10 fs
rlist           = 1.4           ; short-range neighborlist cutoff (in nm)
rcoulomb        = 1.4           ; short-range electrostatic cutoff (in nm)
rvdw            = 1.4           ; short-range van der Waals cutoff (in nm)
coulombtype     = PME           ; Particle Mesh Ewald for long-range
electrostatics
pme_order       = 4                 ; cubic interpolation
fourierspacing  = 0.16          ; grid spacing for FFT

; set temperature to 300K
tcoupl                   = v-rescale
tc-grps                  = system
tau-t                    = 0.1
ref-t                    = 300
; and pressure to 1 bar
pcoupl                   = berendsen
ref-p                    = 1
compressibility  = 4.5e-5
tau-p                    = 5
; generate initial velocities
gen-vel                  = no
;gen-temp                 = 300
;gen_seed                = -1
; Periodic boundary conditions
pbc                 = xyz               ; 3-D PBC
; Dispersion correction
DispCorr        = EnerPres      ; account for cut-off vdW scheme

; COM motion removal
; These options remove motion of the protein/bilayer relative to the
solvent/ions
nstcomm         = 1
comm-mode       = Linear
comm-grps       = system

...................................................................................................


And for Production run, I am using the mdp file as below....


integrator               = md
nsteps                   =10000000
dt                       = 0.001
nstenergy                = 1000
nstxout                  = 1000
nstvout                  = 1000


vdw-type                 = cut-off

continuation    = yes                ; first dynamics run
constraint_algorithm = lincs    ; holonomic constraints
constraints     = all-bonds             ; all bonds (even heavy atom-H
bonds) constrained
;lincs_iter      = 1                         ; accuracy of LINCS
;lincs_order     = 8                         ; also related to accuracy
lincs-warnangle = 90                    ; warning after rotating the bond


ns_type         = grid          ; search neighboring grid cels
nstlist         = 10                 ; 10 fs
rlist           = 1.4           ; short-range neighborlist cutoff (in nm)
rcoulomb        = 1.4           ; short-range electrostatic cutoff (in nm)
rvdw            = 1.4           ; short-range van der Waals cutoff (in nm)

coulombtype     =PME           ; Particle Mesh Ewald for long-range
electrostatics
pme_order       = 4                 ; cubic interpolation
fourierspacing  = 0.16          ; grid spacing for FFT

; set temperature to 300K
tcoupl                   = Nose-Hoover
tc-grps                  = system
tau-t                    = 0.2
ref-t                    = 300
; and pressure to 1 bar
pcoupl                   = Parrinello-Rahman
ref-p                    = 1
compressibility          = 4.5e-5
tau-p                    = 5
pcoupltype              = isotropic
; generate initial velocities
gen-vel                  = no
;gen-temp                 = 300
;gen_seed                = -1
; Periodic boundary conditions
pbc                 = xyz               ; 3-D PBC
; Dispersion correction
DispCorr        = EnerPres     ; account for cut-off vdW scheme

;simulated anneling
annealing         = single
annealing-npoints = 6
annealing-time    = 0 2000 4000 6000 8000 10000
annealing-temp    = 300 310 320 330 340 350

; COM motion removal
; These options remove motion of the protein/bilayer relative to the
solvent/ions
nstcomm         = 1
comm-mode       = linear
comm-grps       = system
cos-acceleration = 0.01


...............................................................

Thanks,
Sabuj


On Mon, Jan 25, 2016 at 12:54 PM, Justin Lemkul <jalemkul at vt.edu> wrote:

>
>
> On 1/25/16 1:51 PM, abdus sabuj wrote:
>
>> Hi Mark,
>> I have equilibrated my system very well before the production run at 300K,
>> but at time zero, the temperature is at 321K.
>>
>> Here is the fluctuations I am getting.
>>
>> time (ns)          temperature (K)
>> 0                  321
>> 2                  315
>> 4                   333
>> 6                   358
>> 8                   377
>> 10                 397
>>
>>
> Please provide the full .mdp file, rather than just the few lines you
> think are important, as well as the commands used to continue from the
> previous run.  You probably have other incorrect settings and/or are
> continuing the run wrong. Time zero should match the previous state; the
> fact that it doesn't suggests you're not doing what you think you're doing.
>
> -Justin
>
>
> Thanks,
>> Sabuj
>>
>> On Mon, Jan 25, 2016 at 12:38 PM, Mark Abraham <mark.j.abraham at gmail.com>
>> wrote:
>>
>> Hi,
>>>
>>> What fluctuations were you seeing over the time segments?
>>>
>>> Mark
>>>
>>> On Mon, 25 Jan 2016 19:25 abdus sabuj <sabujbuetche at gmail.com> wrote:
>>>
>>> Dear gmx users,
>>>>
>>>> I am trying to get viscosity as a function of temperature. So I have put
>>>> the following annealing inputs to the mdp file.
>>>>
>>>> ;simulated anneling
>>>> annealing         = single
>>>> annealing-npoints = 6
>>>> annealing-time    = 0 2000 4000 6000 8000 10000
>>>> annealing-temp    = 300 310 320 330 340 350
>>>>
>>>> i.e, at 10ns, the temperature should be at 350K, right? But I saw after
>>>>
>>> my
>>>
>>>> npt simulation that, the last temperature reached at 400K. Why that's
>>>> happening, did I make any mistakes?
>>>>
>>>> Thanks,
>>>> Sabuj
>>>> --
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> --
> ==================================================
>
> Justin A. Lemkul, Ph.D.
> Ruth L. Kirschstein NRSA Postdoctoral Fellow
>
> Department of Pharmaceutical Sciences
> School of Pharmacy
> Health Sciences Facility II, Room 629
> University of Maryland, Baltimore
> 20 Penn St.
> Baltimore, MD 21201
>
> jalemkul at outerbanks.umaryland.edu | (410) 706-7441
> http://mackerell.umaryland.edu/~jalemkul
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