[Pw_forum] Bond-order-corrected (or BOLS) pseudopotentials

[Cristian Degli Esposti Boschi]

We would like to understand better the so-called bond order length strength (BOLS) correlation approach
[Chang Q. Sun an co-workers, basic ref. is Prog. Solid. State Chem. 35, pag. 1 (2007)] to
structures with under-coordinated atoms (surfaces, ribbons, rods, etc.)

Sometimes it is stated that the BOLS approach is incorportated with DFT calculations, and in particular
quoting from [J. Phys. Chem. C, 112, 18927 (2008)]
"...Unfortunately, the presence and polarization of the
nonbonding states are hardly described from the self-consistent
optimization in DFT or tight-binding approximations at the
present because of the limitation of interatomic potentials.
Potentials suitable for the broken-bond-induced local strain and
quantum trapping that are sometimes several folds deeper than
the potential at the usual atomic site in the bulk and potentials
suitable for the weak interaction between the nonbonding and
the polarized antibonding states are highly desirable for
computations."

It seems to me that they would call for pseudopotentials corrected
by the fact of going to represent atoms with low coordination
or nonbonding states/electrons. Typically, in such a situation,
the neighboring bonds tend to shrink and the bonding energies
(in magnitude) tend to increase.

Should one then consider a "BOLS-corrected" pseudpotential?

Are you aware of problems of this kind, or is the question
correctly posed at all?

Thanks again for your time. Cristian