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Re: [lammps-users] inconsistent vdWaals-parameters Force field parameters for element CA
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Re: [lammps-users] inconsistent vdWaals-parameters Force field parameters for element CA


From: Kristof Bal <kristof.bal@...24...>
Date: Fri, 7 Jul 2017 16:42:53 +0200



2017-07-07 16:06 GMT+02:00 <11637044@...730...>:

Hi all,

I want to use ReaxFF force field to simulate the oxidation of β-isophorone with the presence of Cu-Salen as a catalyst. I got a force field that contains the elements of my simulation(C/H/O/N/Cu).

 Psofogiannakis G M, Mccleerey J F, Jaramillo E, et al. ReaxFF Reactive Molecular Dynamics Simulation of the Hydration of Cu-SSZ-13 Zeolite and the Formation of Cu Dimers[J]. Journal of Physical Chemistry C, 2015, 119(12):6678-6686. (CHONSSiCaCsKSrNaMgAlCu.ff)


And when I run the simulation, I got warnings like this:



Warning: inconsistent vdWaals-parameters
Force field parameters for element CA
indicate inner wall+shielding, but earlier
atoms indicate different vdWaals-method.
This may cause division-by-zero errors.
Keeping vdWaals-setting for earlier atoms.

Warning: changed valency_val to valency_boc for X


I don't understand what "CA" means.(Ca?) Do these warnings mean that this force field is not suitable for my simulation?


Most ReaxFF force field files are full of junk from other parameterizations, such as parameterizations for other elements and other versions of ReaxFF. If they don't involve elements you are interested in, they should be safe to ignore.

But Re:junk: the force field you are intending to use is most definitely not a "CHONSSiCaCsKSrNaMgAlCu" force field. If you look at the abstract of the paper you mentioned, it says: "A new Cu/Si/Al/O/H reactive ReaxFF force field was developed". All other elements that might be present in the force field file are therefore not part of this parameterization, and it is unclear to what extent simulations involving them make any sense.

Kristof
 

Thank you very much.


Luyi Ji



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