[Pw_forum] atomic orbitals

[Nicola Marzari]

On 2/13/11 12:56 PM, David Grifith wrote:
> Dear QE Users
>
> Is it possible that we visualize the atomic orbitals, hybrid orbitals,
> and the overlap between bond orbitals by the Quantum Espresso and its
> side programs like XCrysden ?
> I appreciate your helpful comments in advance. Best Wisehs


QE calculates eigenstates of the Hamiltonian, that you can certainly
visualize.

The orbitals you mention are a conceptualization of what happens as
a chemical bond is formed, and there are no formal definitions
(a part, of course, for atomic orbitals in isolated atoms, that are
eigenstates of the atomic Hamiltonian).

If you perform unitary transformations on the eigenstates that make them 
more local (and not eigenstates any more, but leaving the total energy 
and total charge density unchanged - the occupied manifold is
not affected by unitary transformations) you get orbitals that are
reminiscent of those approximate concepts above - see
www.wannier.org and early biblio. That code works with QE.

As often mentioned in the mailing list, please do sign in full your
posts (i.e. not with acronyms). Thanks!

			nicola

-- 
----------------------------------------------------------------------
Prof Nicola Marzari    Department of Materials    University of Oxford
Chair of Materials Modelling  Director, Materials Modelling Laboratory
nicola.marzari at materials.ox.ac.uk     http://mml.materials.ox.ac.uk/NM