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Temperature skyrocketing for MLFF MD

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Temperature skyrocketing for MLFF MD

Posted: Mon Jan 27, 2025 8:19 am
by mario_Japan

Hi

Currently, MD calculations are being performed using machine learning force fields, but the temperatures are not stabilizing and are rising rapidly. Could you please suggest what the problem is and how to improve it?
Just in case, I am posting INCAR and POSCAR.
I would appreciate your any help :D

Code: Select all

! MD
ISYM = 0 # following warning
LREAL= Auto # following warning



IBRION = 0        ! MD (treat ionic degrees of freedom)
NSW    = 200000    ! no of ionic steps
POTIM  = 5      ! MD time step in fs
NBLOCK = 1                      # (OK)

MDALGO = 3                ! Langevin thermostat
#LANGEVIN_GAMMA   = 1      ! friction
LANGEVIN_GAMMA_L = 10     ! lattice friction
PMASS  = 10               ! lattice mass
TEBEG  = 1273              ! temperature in K
TEBEG  = 1273              ! temperature in K

ISIF   = 2        ! update positions, cell shape and volume

! machine learning
ML_LMLFF  = T
ML_ISTART = 0
ML_WTSIF  = 2

RANDOM_SEED =         688344966                0                0

###AIMD INCAR FILE####
#SYSTEM = Fe-N4-C-AIMD           #System Name
NCORE = 4
NPAR = 8 

#  Prpperotoes:
 LCHARG = .F.
 LWAVE = .FALSE.
 LELF = .FALSE.
 LVTOT = .FALSE.
 LVHAR = .FALSE.
 LAECHG = .F.
 
LDAU = .TRUE.
LDAUTYPE = 2
# Ce O Ni
LDAUL = 3 -1 2
LDAUU = 7.00 0.00 5.10
LDAUJ = 0.70 0.00 0.00
LDAUPRINT = 0
LMAXMIX = 6

Code: Select all

Ce O Ni
1.0
 15.503800000000   0.000000000000   0.000000000000
 -7.751900000000  13.426684655193   0.000000000000
  0.000000000000   0.000000000000  21.329400000000
Ce O Ni
 32  64   4
Selective dynamics
Direct
  0.274650050691   0.289910997118   0.114888437480  F F F
  0.524595943839   0.289824532710   0.114784534556  F F F
  0.774725342089   0.289827346788   0.114697900940  F F F
  0.024758195760   0.289903653205   0.114858954441  F F F
  0.274733005027   0.539958222801   0.114873540452  F F F
  0.524599326341   0.539931816643   0.114795839001  F F F
  0.774701355854   0.539931180038   0.114507841790  F F F
  0.024877273894   0.539952168281   0.114615732413  F F F
  0.274832993150   0.790030390339   0.114871974013  F F F
  0.524717816580   0.790016532472   0.114932902646  F F F
  0.774732293249   0.790094866277   0.114767044827  F F F
  0.024891859505   0.790144257312   0.114652875561  F F F
  0.274746927444   0.039987440873   0.114891820259  F F F
  0.524712183662   0.039909616295   0.114902545696  F F F
  0.774744345387   0.039975613924   0.114933346940  F F F
  0.024772226639   0.040067394523   0.114889533141  F F F
  0.186057203507   0.370775879899   0.261755377638  T T T
  0.437957803308   0.367905839696   0.262930026872  T T T
  0.693435007042   0.369760050566   0.261233206858  T T T
  0.941719698660   0.373280272446   0.261208997242  T T T
  0.191039865744   0.623976945440   0.261081667934  T T T
  0.439001484841   0.626196860647   0.263054346974  T T T
  0.696496257479   0.625801143879   0.259399181493  T T T
  0.942202548663   0.623118939943   0.260432729674  T T T
  0.190822627753   0.873026898341   0.260497435203  T T T
  0.440037365233   0.873655275854   0.261302841806  T T T
  0.693379044395   0.878920644167   0.261553201794  T T T
  0.942207533203   0.874261837720   0.260728034363  T T T
  0.191007164760   0.122143639379   0.261210237634  T T T
  0.440135535648   0.121812689076   0.261278836849  T T T
  0.691212578518   0.123260809186   0.261797377818  T T T
  0.941812697725   0.123718634120   0.261419981203  T T T
  0.108050955949   0.206630211680   0.077857433969  F F F
  0.357971085472   0.206561639483   0.077854755277  F F F
  0.607989583500   0.206480392923   0.077799736329  F F F
  0.858086672941   0.206545548666   0.077811063872  F F F
  0.108142353607   0.456591088432   0.077783916836  F F F
  0.357960721300   0.456592688594   0.077871484838  F F F
  0.607914613529   0.456535181037   0.077791885954  F F F
  0.858111858417   0.456532612344   0.077676192902  F F F
  0.108261926514   0.706743601237   0.077730470243  F F F
  0.358101684489   0.706680631567   0.077857431656  F F F
  0.607995454003   0.706717398399   0.077870522366  F F F
  0.858119572078   0.706780339371   0.077730308646  F F F
  0.108162437995   0.956784921549   0.077812869193  F F F
  0.358107649490   0.956653807362   0.077844659707  F F F
  0.608065134268   0.956644911169   0.077874798078  F F F
  0.858094297145   0.956766685638   0.077859006936  F F F
  0.191363564286   0.373277708838   0.151949054020  F F F
  0.441251227983   0.373205321113   0.151860526475  F F F
  0.691285567236   0.373135848253   0.151583610380  F F F
  0.941454146075   0.373216701292   0.151718633361  F F F
  0.191543731060   0.623379508980   0.151846672105  F F F
  0.441332576841   0.623341806392   0.151927229624  F F F
  0.691285642930   0.623331076748   0.151625356885  F F F
  0.941539000884   0.623379691954   0.151370449048  F F F
  0.191544659060   0.873406735383   0.151872612435  F F F
  0.441412773198   0.873316778858   0.152004600248  F F F
  0.691352146133   0.873383233365   0.151965242737  F F F
  0.941456172398   0.873467845650   0.151761164011  F F F
  0.191377836877   0.123303201916   0.151973602490  F F F
  0.441322893478   0.123194343963   0.151933714214  F F F
  0.691344432930   0.123173920223   0.151920848521  F F F
  0.941376078055   0.123299180501   0.152006016210  F F F
  0.270387337789   0.289042050557   0.224186201072  T T T
  0.528801729234   0.289588180581   0.224640739985  T T T
  0.774935014685   0.289807021888   0.222856972546  T T T
  0.023923994557   0.289611864155   0.222708422059  T T T
  0.270521164517   0.536651861432   0.224223792058  T T T
  0.532773954888   0.543859170952   0.227691066314  T T T
  0.773023146813   0.538732334534   0.223119465745  T T T
  0.024449433695   0.540069596733   0.222624490742  T T T
  0.273026998723   0.790901424371   0.222145557764  T T T
  0.528528834365   0.794694901142   0.224498080214  T T T
  0.772965452951   0.789380530298   0.223485735547  T T T
  0.024505860891   0.789834721564   0.222408352361  T T T
  0.273093683050   0.037499896738   0.222070375736  T T T
  0.525052265026   0.040242809391   0.223347646026  T T T
  0.774979231410   0.040477453737   0.223099672798  T T T
  0.024786268284   0.039621233990   0.222978358380  T T T
  0.104249576899   0.205233137992   0.299370426802  T T T
  0.351232747149   0.193391691007   0.299982876302  T T T
  0.610975914887   0.206182681805   0.300031121419  T T T
  0.858665963660   0.207095175722   0.298354696022  T T T
  0.104137835028   0.454428571326   0.299269508174  T T T
  0.342721326640   0.448657921418   0.316034898822  T T T
  0.623825566519   0.459429431225   0.313168970651  T T T
  0.858940306320   0.456191480334   0.297992615740  T T T
  0.105864820391   0.705898517284   0.298046259677  T T T
  0.351220699125   0.713173876114   0.299914381421  T T T
  0.621826087004   0.720350376404   0.312783111211  T T T
  0.859136332103   0.707030972955   0.297701111116  T T T
  0.106100476017   0.955149579114   0.298360181370  T T T
  0.357790213529   0.956640573055   0.298065159108  T T T
  0.610938964765   0.960334119436   0.299989916791  T T T
  0.859388092073   0.958105302860   0.298081704900  T T T
  0.644606725385   0.424476601957   0.403272894495  T T T
  0.791421966144   0.415247252421   0.400555248905  T T T
  0.636017012609   0.265530962860   0.404179840482  T T T
  0.693435007042   0.369760050566   0.495651427717  T T T

Re: Temperature skyrocketing for MLFF MD

Posted: Mon Jan 27, 2025 8:46 am
by alexey.tal

Dear mario_Japan,

Thank you for your question.

Could you please provide all relevant input and output files for your calculation according to the forum guidelines?

Best wishes,
Alexey

Re: Temperature skyrocketing for MLFF MD

Posted: Thu Jan 30, 2025 9:56 am
by mario_Japan

Dear Alexey
Sure, I attached documents.
Also, I updated the latest temperature results. is there any way to make the temprature stable at target value?

Re: Temperature skyrocketing for MLFF MD

Posted: Thu Jan 30, 2025 1:22 pm
by alexey.tal

I noticed that you set LANGEVIN_GAMMA_L, which controls the friction and stochastic terms applied to the lattice. However, LANGEVIN_GAMMA controls the friction and stochastic terms applied to the velocities. If you actually want to use NVT ensemble, which you select with ISIF=2, you should set LANGEVIN_GAMMA, not LANGEVIN_GAMMA_L. If you would like to use NpT ensemble, you need to set ISIF=3, which allows to relax the cell.

Furthermore, the time step in your simulation might be too large, which could result in a numerical instability of the MD run, so I would recommend you setting POTIM to a smaller value, for example 1 fs.

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