[Pw_forum] My vague understanding of internal degrees of freedom

[xiaochuan Ge]

Dear Hongsheng Zhao,
I am not sure about what you want to ask. But I guess if what you mean
by "internal degrees" is what you have specified, a system having or
not having the internal degrees does not depend on the shape of of the
cell.  You may check the input description of pw.x, I think the "no
internal degrees of freedom" is mentioned for scf calculation is
because in "relax" the atomic coordinates are allowed to evolve during
the calculation, while when scf is specified only electronic
configurations have the freedom to evolve keeping all the atomic
coordinates fixed.
I hope that I have answered your question, excuse me if I have
misunderstood your real puzzle.
Best wishes,
Ge Xiaochuan

2011/7/22  <pw_forum-request at pwscf.org>:
> My vague understanding of internal degrees of freedom