[gmx-developers] MC with PME

[André Assunção S. T. Ribeiro]

Dear all, 

I have been working to implement a Monte Carlo "integrator" for GROMACS. For the last couple of months I've been trying to improve performance of the algorithm. For that end, I have made adaptations to the ns and force evaluation routines. Energies for each interaction are stored separately, so one can just calculate the needed energy terms in each trial move. When treating nonbonded interactions with a cutoff, MC performance is more than 10-fold greater than MD for a simple system containing 216 SPC waters (by performance I mean number of simulation steps/CPU time, not actual sampling efficiency). When I use PME, the situation is far worst, with an approximate 3-fold increase. When I try to call gmx_pme_do for only a small number of atoms performance decreases when compared to the total calculation. For simple Ewald sum, there is a 10-fold increase when a single molecule is calculated, however, it is still a lot slower than the worst PME result. Would anyone have any ideas on how to increase performance here? 

Cheers, 
Andre. 

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