How to estimate QMMM box dimensions

Tianshu Jiang in Beijing jts2t... at
Thu Dec 21 11:13:19 UTC 2017

hello Hardikar,

The dimension of QM box depends on your system, or the quantity where you 
are interested. 
You can refer the paper "An Efficient Real Space Multigrid QM/MM 
Electrostatic Coupling" written by Teodoro Laino for details.
The realization of QMMM in CP2K is based on this paper.

Best wishes !

在 2017年12月20日星期三 UTC+8下午6:06:37,Rahul Hardikar写道:
> Dear CP2K Users/Experts,
> Currently, in my QMMM setup I am maintaining box lengths same as the 
> overall systems' box lengths. I am aware that one can reduce the box size 
> for the QMMM
> box thereby reducing the cost of QM calculations. However what is not 
> clear to me is the role of electrostatics when QMMM box lengths are less 
> the the overall lengths. So my question is (a) how one can estimate the 
> QMMM box lengths and maintain the electrostatic interaction between QM and 
> MM part consistent? and (b) how can I estimate the amount of vacuum to use 
> to avoid any interaction between periodic images? I am using cubecruncher 
> to crunch out plane averaged electrostatic potential and hartree energy 
> from the corresponding cube files.  
> Any suggestions and/or comments will be appreciated.
> Best Regards,
> Rahul Hardikar
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