Hi, everyone

I have a question about the concept of pressure.

Generally there are two ways to calculate the pressure along one axial direction for crystalls. One is Viral theorem which is commonly used in **LAMMPS**, another is to calculate the first order of total energy (dE/dl) which is often used for first-principle calculations.

My questions are

(1) Whether the two methods are equivalent (although they can be derived from each other)

(2) Which of them is better numerically

Thanks!