NPT equilibration - very high pressure

Dear Team,

I hope if you can help me with my problem and in all ways thank you for your enormous help in this mailing list.

After energy minimization, I was trying to equilibrate my system with NPT ensemble at 300 K at P=0 with “metal” units. I used the following commands but the pressure during simulation is extremely high and was equilibrated P=3800 bar. Can you pleased advise if i am applying the equilibration technique in a wrong way or not?

min_style cg
minimize 1e-25 1e-25 5000 100000

Step Atoms Temp Press PotEng KinEng TotEng Volume Density
8 1566 300 3430.0525 -4304.4565 60.687638 -4243.7688 14097.888 4.6156103
100 1566 300 3430.0525 -4304.4565 60.687638 -4243.7688 14097.888 4.6156103
200 1566 300 3430.0525 -4304.4565 60.687638 -4243.7688 14097.888 4.6156103

1000 1566 300 3430.0525 -4304.4565 60.687638 -4243.7688 14097.888 4.6156103
1008 1566 300 3430.0525 -4304.4565 60.687638 -4243.7688 14097.888 4.6156103

fix 1 all npt temp 300.0 300.0 100 aniso 0.0 0.0 1000

1008 1566 300 3430.0525 -4304.4565 60.687638 -4243.7688 14097.888 4.6156103
1100 1566 265.962 3962.7618 2210.6141 53.802018 2264.4161 14097.888 4.6156102
1200 1566 256.76105 4928.4334 4541.8625 51.94074 4593.8033 14097.889 4.61561
1300 1566 267.04746 5274.6659 3633.5111 54.021599 3687.5327 14097.89 4.6156097
1400 1566 279.8136 5215.5371 1841.4099 56.604088 1898.014 14097.891 4.6156093

Thanks in advance

Dear Team,

I hope if you can help me with my problem and in all ways thank you for
your enormous help in this mailing list.

After energy minimization, I was trying to equilibrate my system with NPT
ensemble at 300 K at P=0 with "metal" units. I used the following commands
but the pressure during simulation is extremely high and was equilibrated
P=3800 bar. Can you pleased advise if i am applying the equilibration
technique in a wrong way or not?

​impossible to say based on so little information.

axel.​

The time constant of pressure equilibration is 1 NS in your input, meaning that you’d only see appreciable pressure changes after very long runs. So what about trying more appropriate values for these damping constants?

Kristof