The tregime.in file
When the tregime.in file is present during an MD simulation, you can change the temperature of the system as the simulation proceeds.
You can heat up the system by specifying what the temperature should change to at particular time steps.
(See ~jkua/reac/MDtemp3/xtalheatto300K/ for an example.)
#Temperature regimes
#start #T at1 at2 T1 Tdamp1 dT1 at3 at4 T2 Tdamp2 dT2
0 1 1 400 10.0 100.0 0.00
10000 1 1 400 20.0 100.0 0.00
20000 1 1 400 30.0 100.0 0.00
30000 1 1 400 40.0 100.0 0.00
40000 1 1 400 50.0 100.0 0.00
50000 1 1 400 60.0 100.0 0.00
60000 1 1 400 70.0 100.0 0.00
70000 1 1 400 80.0 100.0 0.00
80000 1 1 400 90.0 100.0 0.00
90000 1 1 400 100.0 100.0 0.00
For this 400-atom simulation, it means at step 0 (#start), the number of temperature regimes you have is 1 (#T) involving atoms 1 (at1) to 400 (at2), the temperature should be 10.0 K and the the damping factor (which should have been smaller) is 100.0 K. In step 10000, the temperature is raised to 20 K. In step 20000, the temperature is raised to 30 K.
You can follow the output in fort.75, for example which is quite self-explanatory.
You run this job similar to an MD simulation. Don't forget to specify the appropriate MD simulation parameters too.