Timeline for Software to simulate and visualize atoms?
Current License: CC BY-SA 3.0
13 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Mar 19, 2016 at 15:38 | history | made wiki | Post Made Community Wiki by Qmechanic♦ | ||
| Apr 12, 2012 at 20:02 | vote | accept | MaiaVictor | ||
| Jan 11, 2012 at 11:20 | comment | added | Richard Terrett | Correcting my earlier statement: nuclear wavefunction and B.O. can happily coexist, according to a researcher in the field. | |
| Jan 3, 2012 at 13:35 | comment | added | Ron Maimon | @Jen: It is not tautological if the range of validity is essentially the empty set, when the only things that work are the calibrating examples. Is there one case where atomic-force MD is correct outside its calibrating set? | |
| Jan 3, 2012 at 13:22 | comment | added | Jen | @RonMaimon - it is tautological to point out that a method used outside of its range of validity will not provide reasonable answers. | |
| Jan 3, 2012 at 12:19 | comment | added | Ron Maimon | @Richard Terrett: I believe that it is certainly the only "ab initio MD" method, it is shocking enough that one exists! To do electronic flows with any sort of realism on the fly is, on its face, impossible. I would have been content with a molecule-by-molecule ad-hoc parametrization of the potential surface for large-scale shape deformations, plus a local potential approximation, or even a conducting/nonconducting region volume/bending energy model. Born/Oppenheimer is the last thing to worry about at room temperature. Anyone using a nuclear wavefunction is basically a fool. | |
| Jan 3, 2012 at 12:07 | comment | added | Richard Terrett | @RonMaimon - Glad CPMD was of interest to you. It's certainly not the only 'ab initio MD' method but it seems the state of the art is very experimental. I saw a few lectures recently on 'quantum dynamics' which take traditional ab initio calculations into the time evolution realm but it seems fairly bleeding edge, e.g. AFAIK the Born-Oppenheimer approximation needs to be replaced with a nuclear wavefunction. Incidentally, this is just mind-boggling: petachem.com/demo.html | |
| Jan 3, 2012 at 6:49 | comment | added | Ron Maimon | @Jen: It is important to say flat out that the MD codes, leaving aside CPMD, are no good, because the electronic fluid is mis-simulated, leading to much more floppy molecules than the ones you find in nature. Further, only CPMD can deal with bond-breaking and reforming. It is the only correct simulation method. Combined with a good nonlocal electrodynamic force model and a good coarse-grained in time stochastic updating, it gives the only complete answer to the question. | |
| Jan 3, 2012 at 6:19 | comment | added | Ron Maimon | @Richard Terett: That's interesting, I didn't know this method, but reading the description, if you implement it well, it should be the ideal way to deal with the main issue of electronic delocalization. But there is also the less pressing issue of nonlocal electromagnetic forces, which is important also for large molecules. The final issue is with the stochastic approximation. Thanks for the pointer. | |
| Jan 2, 2012 at 11:57 | comment | added | Richard Terrett | @RonMaimon - Car-Parinello molecular dynamics is a level of theory that combines electronic structure with MD, and is implemented in codes such as CPMD. | |
| Jan 2, 2012 at 9:02 | comment | added | Ron Maimon | Nothing but MD gives a time-dependent picture as far as I know. | |
| Jan 2, 2012 at 6:12 | history | edited | Jen | CC BY-SA 3.0 |
added 8 characters in body
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| Jan 2, 2012 at 6:05 | history | answered | Jen | CC BY-SA 3.0 |