What's the difference between displacement and vectors?

[pobo95]

Thank you for your great work!

I'm studying your code these days.

So what is the difference between displacement and vectors?

It seems like

$$vectors=r_j-r_i$$

but I have no idea about displacement, can you give me some help?

Thanks!

[ilyes319]

Displacement is displacing the cell. It used to compute the stresses/virials.

[bernstei]

Those names are, if anything, the opposite of what I'd expect. I strongly suggest changing them. "vectors" sounds more like "cell vectors", and I know that atomic positions are also vectors, but that word isn't used explicitly for them as much. And "displacement" really suggests displacing atoms.

Can we add "position" or "pos" to "vectors", and maybe change "displacement" to "cell_deformation" or something? Is it the deformation gradient, in fact?

[pobo95]

I checked
stresses/virials is

$$d(energy) \over d(displacement)$$

then displacement means changes of cells?