I am having trouble to set up heating using charmm/openmm implementation and need some help. For a fixed temperature, I can run NVE/NVT/NPT with charmm/openmm implementation without any problem. However, when temperature changes (for heating process), the temperature control seems not working and it dies in the first several steps (with error Energy is NaN). Below you can find my script. I would be very thankful if anyone can instruct me what I did wrong or share with me a working script for heating using charmm/openmm.
Thank you very much.
set t1 8.0
set t2 298.0
set mdstep 8000
dynamics leap start -
nstep @mdstep timestep 0.002 -
iunrea -34 iunwri 33 iuncrd 32 kunit -1 -
isvfrq 1000 nsavc 1000 nprint 1000 -
ntrfrq 1000 iprfrq 2000 ixtfrq 1000 ilbfrq 1000 -
firstt @t1 finalt @t2 tstruc @t1 -
teminc 5.00 ihtfrq 100 ieqfrq 100 iasor 0 iasvel 1 iscvel 0 -
ichecw 1 twindh 5.0 twindl -5.0 -