Hi joanne and others,
I have something new. Someone advised me to use these commands: “velocity all set 0 0 0; fix 1 all npt 300 300 0.1 xyz 0 0 0.1 drag 1.0”. The results were really perfect, the temperature increased from 1e-23 to 300 K and keeped this value without fluctuation, and the pressure decreased to zero rapidly, the magnitude of the final pressure value was 1e-6. But with the same fix, I used this “velocity all create 300 5812775 temp new3d”, the temperature fluctuated around 300K, and the magnitude of final pressure value was 1e+2.
So I want to know, with the same fix, why is there so much difference between these two cases with different velocity commands?
Another question is whether these two cases are both ok?