[blix]

I would not describe AMBER, or anything using a newtonian force field, as ab initio.

In inorganic materials ab initio means you actually solve Schrodinger's equation (though obviously with aggressive simplifications e.g. Hartree-Fock).

[dekhn]

Sure. But in the protein structure prediction field, "ab initio" is used to mean "structure was predicted with no homology or other similarity information" even though the force fields incorporate an enormous amount of protein structural knowledge.

[blix]

I guess it's just wierd to me to see ab initio used to describe a class of methods than in my field it explicitly precludes.

Having developed a few newtonian force fields, calling them "derived from QM" is very, very generous :P