Physics vs Chemistry

March 28, 2007

Having a background in chemistry and working with a group of physicists is interesting. They may have their fancy models, but we have our chemist’s intuition! One of the biggest differences I have noticed so far is the use of symmetry.

In terms of crystal lattices, I am more used of thinking in terms of conventional unit cells with lattice vectors along cartesian axes. Primitive cells for centered crystals make more sense in terms of the cost of calculations (and for calculation of band and phonon dispersion), but they are harder to visualize and construct - especially for body-centered monoclinic cells that I am currently concerned with.

I happened to come across a nice free package called Lev00. It can work with VASP, Crystal and Siesta. So far I have only used the subprogram Tetr which can produce primitive cell structure files based on previously generated VASP POSCAR files, or work directly from crystallographic data. Very handy! It seems to do a lot of other nifty things, I just haven’t had a chance to use them yet. The source code is available here.

I also picked up another nice book for $16 on amazon. “Group theory and quantum mechanics”. It is a reprint of a book from the sixties (I don’t think too much has changed since then in group theory). It’s small and concise. It reads like a lecture series, and it’s definitely not pop science. It would be good to have some basic background on group theory before starting. There are some nice references to old Physical Review papers along the way, for when more detail is needed.