conserved quantity in QM/MM run

Teo teodor... at gmail.com
Mon Aug 4 11:20:13 CEST 2008


Hi,

qmmm interaction potential is computed within the first image cell.
This by
definition cannot led to conserved quantity if you are studying a
condensed phase system
(you can trivially understand why)!
If you want that, you've to use the PERIODIC version of the qmmm
module and
first of course get acquainted with it (see papers and so).

Teo


On Aug 4, 11:02 am, Bart De Sterck <bartde... at gmail.com> wrote:
> Hi,
>
> we are performing md simulations on water with the purpose of
> eventually studying the solvation of our target molecules. For this
> aim, we first performed an MM simulation (NVE, NVT using the nosé-
> hoover thermostat) using the TIP3P model in which the conserved
> quantity is conserved indeed.
>
> To get acquinted with the QMMM routine, we performed a simulation in
> which one of the water molecules was treated on the BLYP level of
> theory. In this simulation however, either using the NVE or NVT
> ensemble, we were unable to obtain a constant conserved quantity.
>
> We added to the file repository an input file for the NVE simulation
> using the 15/07/2008 version of cp2k, together with graphs of the
> relevent parameters during our 5 ps MD run.
>
> What are we doing wrong? We are looking forward to all suggestions.
>
> best regards
>
> Reinout Declerck and Bart De Sterck


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