Ramblings of a computational materials chemist
August 2, 2008
In me are hidden constellations
Once I managed to sight one
through a lens of equations
that could be solved only
approximately. Still,
with that imperfect rule
I taught others the electrons’
lobed motions. I’m wrong, often,
I work this wild chemical
garden with one old tool.
Let me show others the way to see.
An extract from ‘Somewhere’ by Roald Hoffmann.
July 4, 2008
Sinking into the routine of Colorado life means that time has been passing much faster than last year. Strange to think that 18 months have passed since I arrived at NREL. It really is an excellent place to work and focus on research: there are no students, lectures or grading to worry about, and the project directions are very dynamic compared to university. This has resulted in my publication backlog being well-flushed this year. We have a number of papers in press on transparent conductors, II-VI alloys, dilute magnetic semiconductors, and lithium intercalation in oxides (some more controversial than others). I’m aware that I’m very fortunate to be in a position to have so many excellent collaborators both experimental and theoretical. Papers are great, but it’s time now for some real breakthroughs....
April 26, 2008
New Orleans is quickly turning into my second home. From attending two conference there in the last month, the major differences between the American Chemical Society and the American Physical Society became apparent: ACS has more $$$$. From a welcome band at the airport, to billboards all around downtown, and of course ACS TV on the coaches, this was a much more *bling* affair. Being an energy themed conference, there was also a wealth of great talks. The keynote was from the Undersecretary of Energy, who gave a nice overview of all the areas of renewable energy that DOE are presently focused on. In the same session there were talks representing the highlights from a number of the inspiring Basic Energy Research Needs Workshop series: http://www.sc.doe.gov/bes/reports/list.html. With so many parallel oral sessions, and thousands of posters, it’s nice to be back home to the tranquility of Denver.
March 30, 2008
Peer-reviewing publications is generally an enjoyable process, especially being a developing scientist, as it gives you some exposure outside your local safety box. Being peer-reviewed, in principle, can offer even more benefits: an informed critique of your work, along with some useful suggestions to make the manuscript more accessible to the community at large. Frequently this is the case, but sometimes you end up with someone who obviously is working along similar research lines and savors the opportunity to unleash a vendetta concentrating all the anger from their unfulfilling life. Would double-blind reviews solve this? Probably not. One reader in the APS magazine last month suggested reverting to the (g)olden days when both the reviewers and their comments would be published in the appendix along side the manuscript. Of course this would create just as many problems, but it’s a nice thought.
I enjoyed the APS this year more than last. Maybe it’s because I was presenting this time, or all the tasty seafood in New Orleans. Getting to put faces to names is the best part, especially meeting up with collaborators who were only 1’s and 0’s before. After a couple of referee hiccups, the paper I presented got accepted to PRL. Now a week to prepare before it’s back to Louisiana for the ACS Spring meeting.
March 1, 2008
Thomson’s Web of Science (WOS) is obviously a useful tool. Those of us born post-1980 have heard the dreaded tales of trying to follow citations through printed copies of Chemical Abstracts (fun times). With the advent of RSS feeds and citation databases such as Endnote and Bibtex, keeping up to date with current research and writing well referenced papers becomes almost effortless. The major flaw in WOS is trying to follow the works of one author. It’s tough enough for initial-less authors such as myself (I wish I had been forewarned before publishing my first paper), but if they are Asian, just give up. So to complement WOS, Researcher-ID emerged. Anyone can freely register, state your current affiliation and link all published works on Web of Science. Hopefully this will eventually be fully integrated so that author-sets automatically appear when searched in WOS. The membership seems quite low at the moment, but here I am. Perhaps this marks the beginning of scientific social networking?
In seven days I ship off to New Orleans for the APS meeting and also tick another year off on my life’s punch-card. Twenty six is too close to thirty for my liking.
January 14, 2008
It’s a new year, and a good time to review the current status of periodic DFT simulation codes. If I'm missing some important codes, please comment.
a. (plane wave codes)
VASP (Commercial). Tested PAW/p.p. database. MD. Elastic band. Stress.
ABINIT (Academic). PAW/p.p. MD. Stress. TD-DFT. GW. Optical.
CASTEP (Commercial) Elastic band. MD. Optical. Stress.
QUANTUM-ESPRESSO (Academic) Elastic band, MD. Next version: PAW, Hybrid-DFT.
CPMD (Academic) Flexible MD, TD-DFT.b. (all electron codes)
b. (all electron codes)
WIEN2K (Commercial). LAPW. Advanced optical analysis. Limited Hybrid-DFT.
EXCITING (Academic). LAPW. Hybrid and full HF calculations.
FLEUR(Academic). LAPW.c. (gaussian basis set codes)
c. (gaussian basis set codes)
CRYSTAL (Commercial). Hybrid-DFT, HF. Slow. Relativistic cores can be tough to find.
d. (linear scaling codes)
SIESTA (Academic). Efficient numerical basis set. MD. P.P./basis set database is limited.
CONQUEST (Academic). Plane waves / numerical basis. Tight binding / full DFT.
ONETEP (Academic). Density matrix. Wannier functions.
DMOL(Commercial). Numerical Basis. All-electron/cores. Interaction cutoff. Optical.e. (transport codes)
e. (transport codes)
SMEAGOL (Academic) Linked into SIESTA.
WANNIER-TRANSPORT(Academic) Linked into Quantum-Espresso.f. (codes you’d never really want to use)
f. (codes you’d never really want to use)
GAUSSIAN (Commercial). The workhouse, and nightmare to compile, molecular code has limited support for periodic systems. Just don’t publish the results against any other code, or you’ll be on their blacklist for life (http://www.bannedbygaussian.org).