May I ask what’s the difference between these two methods for calculating pressure?
compute 1 all pressure thermo_temp
thermo_style pxx pyy pzz pxy pxz pyz
As far as I know, the first one includes 6 elements, but if these 6 elements are calculated in the same way as them in 3) ?
May I ask what's the difference between these two methods for calculating
none. it is explained in the thermo_style documentation.
In addition to reading the documentation, if you are still curious, try doing some numerical experiments. LAMMPS gives a lot of different options for computing the pressure, that’s why there is often more than one way to get the same result.