[CP2K-user] NPT volume error when using beryllium in molten salts

[Travis]

Hi,

I would not recommend smoothing with NPT, refer to 
https://aip.scitation.org/doi/abs/10.1063/1.4986284. You *may* need a 
ludicrously excessive cutoff compared to not using smoothing at all for 
reasonable densities.

First iteration, delete this bit and see if your result improves (you might 
see improvement even with a quicker CELL_OPT),
      &XC_GRID
        XC_DERIV        SPLINE2_smooth
        XC_SMOOTH_RHO   NN10
      &END XC_GRID

-T

On Monday, January 6, 2020 at 5:21:04 PM UTC-5, Austin clark wrote:
>
> Hi all,
>
> I'm running some AIMD simulations on molten salts using the NPT ensemble. 
> Typically, the equilibrium cell volumes correspond to liquid densities that 
> agree well with experiment. However, I'm currently working with a salt that 
> consistently yields an equilibrium volume that is much lower than 
> experimental models predict. The only difference I can really see is that 
> this salt contains beryllium, and our others do not. Our other salts used 
> only alkali cations. Beryllium is also known to form a unique structure in 
> this salt, and qualitatively we see that, but our equilibrium volume is 
> still off by about 5%. Any idea what is happening?
>
> Thanks,
> Austin
>
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