Hi everyone:
I want to give you a heads-up about a new thermostat we are working on. It's
based on the Langevin idea of adding a random-force componenent, but borrows
an idea from quantum computing: the extra forces can represent several
different temperatures at once. This has some important implications. For
example, if your dynamics undergoes spontaneous conformational transitions
(e.g trp-cage folding/unfolding) then you can extract the entire temperature
dependence from a single run. Or (for more complex sampling problems)
temperature replica exchange simulations can be carried out with a single
replica.
This is not yet ready for general use, but the basic ideas have been
implemented in sample code. Right now, it doesn't work with SHAKE
constraints, and the some instabilites set in if you have more than a few
dozen temperatures in a single run. But we can get (SPC-fw) water to go from
supercooled to just under boiling: this is not a classical cycling of
temperature from low to high values, but a true quantum-like superposition of
temperatures.
(Dave Cerutti thinks he can make a barostat do the same thing.)
...details later....dac
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Received on Fri Apr 01 2011 - 05:30:03 PDT
