[gmx-users] lmc-stats

2013-10-28 Thread Andrew S. Paluch
When performing free energy calculations using the expanded ensemble 
method, there is a barker and metropolis option for lmc-stats. Are the 
corresponding transition probabilities computed with or without the 
weighting factors? That is, are these probabilities biased or not?


Thank you,

Andrew

--

Andrew S. Paluch, PhD
Department of Chemical, Paper, and Biomedical Engineering
Miami University
paluc...@miamioh.edu
(513) 529-0784
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Re: [gmx-users] lmc-stats

2013-10-28 Thread Michael Shirts
Hi, Andrew-

The choice of lmc-stats only affects the calculation of the weights,
it does not affect the calculation of the transition matrix.

There are two possibilities for the transition matrix; the estimated
one (which is just called 'Transition Matrix' -- we should probably
have a better name), and the empirical one.  The empirical transition
matrix is just transition counts. The first one is an ensemble average
of P(k|x); for neighbor moves, this is just the average of the barker
transition probabilities (plus the choice of going up or down),

Let me know if this is useful.  Not that many people have used this
code, thus there are likely ways that it can be improved for better
utility.  I generally haven't tried to calculate free energy
differences from the transition matrix, though it should give
consistent results with the other methods.

Best,

Michael Shirts
Assistant Professor
Department of Chemical Engineering
University of Virginia
michael.shi...@virginia.edu
(434)-243-1821

On Mon, Oct 28, 2013 at 11:13 PM, Andrew S. Paluch paluc...@miamioh.edu wrote:
 When performing free energy calculations using the expanded ensemble method,
 there is a barker and metropolis option for lmc-stats. Are the corresponding
 transition probabilities computed with or without the weighting factors?
 That is, are these probabilities biased or not?

 Thank you,

 Andrew

 --

 Andrew S. Paluch, PhD
 Department of Chemical, Paper, and Biomedical Engineering
 Miami University
 paluc...@miamioh.edu
 (513) 529-0784
 --
 gmx-users mailing listgmx-users@gromacs.org
 http://lists.gromacs.org/mailman/listinfo/gmx-users
 * Please search the archive at
 http://www.gromacs.org/Support/Mailing_Lists/Search before posting!
 * Please don't post (un)subscribe requests to the list. Use the www
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