CCL: QM/MM computational cost?

 Sent to CCL by: Guilherme Menegon Arantes [garantes],[iq.usp.br]
 On Thu, May 18, 2006 at 01:21:47PM -0400, Ross Walker ross]|[rosswalker.co.uk
 wrote:
 > Sent to CCL by: "Ross Walker" [ross|*|rosswalker.co.uk]
 >
 > [.....]
 > before it even starts to become expensive. Plus you can do a simulation
 with
 > a full treatment of electrostatics and periodic boundaries for both the QM
 > and MM regions using PME. Without a PME treatment you will need to use an
 > infinite (i.e. no) cutoff and probably add an implicit solvent treatment
 for
 > the gas phase region of your system to get meaningful results. Using a cut
 > off with gas phase / water cap simulations introduces serious artefacts
 into
 > your simulation and can completely invalidate your results. Hence often it
 > can be quicker to do a full PME treatment than to run the gas phase
 > non-periodic simulation.
 > [.....]
 I would appreciate if you could point me to any references showing this
 explicitely.
 In my experience, properties (say, PMF) calculated in QM/MM simulations
 with some truncation schemes, in particularly atom-based force-switching,
 with reasonable cut-off radius, are equivalent to the properties
 obtained without any truncation.
 G
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 Dr. Guilherme Menegon Arantes        Sao Paulo, Brasil
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