stopping simulation for dm/dt=0?

[Vinod Naik Bhukya]

Is there a way in vampire that we can specify in the input file to check for dm/dt=0 instead of specifying the loop time steps. Based on the time step and the loop time steps, the simulation will end only after the specified time has elapsed, but I would like to stop the simulation once dm/dt=0. Is there a way?

[gabo...@gmail.com]

I believe "No" is currently the answer.

Is this in regards to a particular sim:program?

Page 47 (pdf page 48) in the VAMPIRE 7.0 manual [1] has:

sim:program = static-hysteresis-loop

...

At each field increment the system is integrated until either the maximum torque for any one spin is less than the tolerance value (10^−6 T), or if sim:loop-time-steps is reached.

You may need Dr. Evans to confirm, but to set dm/dt to stop at a value greater than 10^-6 T when using "sim:program = static-hysteresis-loop", it may be currently line 118 of the static_hysteresis.cpp file in the develop branch source code [2] that you should have to adjust and recompile:

line 118: if((torque<1.0e-6) && (sim::time-start_time>100)){
line 119: break;
line 120: }

Similarly for "sim:program = LaGrange-Multiplier", it's likely line 138 of lagrange.cpp [3] with:

line 138: if((torque<1.0e-6) && (sim::time-start_time>100)){

Hopefully that helps.

[1] https://vampire.york.ac.uk/resources/vampire-manual.pdf 

[2] https://github.com/richard-evans/vampire/blob/develop/src/program/static_hysteresis.cpp

[3] https://github.com/richard-evans/vampire/blob/develop/src/program/lagrange.cpp

Kind Regards,

Gavin

VAMPIRE user

[Vinod Naik Bhukya]

Thank you for your reply. I need this in  sim: program=time-series. 

gabo...@gmail.com 在 2026年4月16日 星期四上午11:27:30 [UTC+8] 的信中寫道：

[gabo...@gmail.com]

In time_series.cpp [1], I'm not seeing any stopping criterion code for dm/dt.  On the other hand, it does look like a time stopping criterion is there on line 74:

Line 74:  while(sim::time<sim::equilibration_time+sim::total_time){

It looks like that will stop when the simulation time becomes larger than the sum of the equilibration time and total time.

[1] https://github.com/richard-evans/vampire/blob/develop/src/program/time_series.cpp

Kind Regards,

Gavin

VAMPIRE user

[Vinod Naik Bhukya]

Thank you. I think it's not possible to stop when dm/dt=0 for time series.

gabo...@gmail.com 在 2026年4月18日 星期六凌晨2:19:40 [UTC+8] 的信中寫道：