[DFTB-Plus-User] Deuterium mass assigned to hydrogen

[daniele.veclani at isof.cnr.it]

Dear users,

 

I am performing an MD simulation with DFTB+ 21.2 of the water interaction
with a surface. The level of theory is SCC-DFTB and the timestep 0.5 fs, NVT
300 K with Nose-Hoover, Matsci + mio S-K parameters. I was wondering if with
this method is recommended to assign the deuterium mass to hydrogen, as
usually happens for ab-initio MD at other levels of theory (e.g. BOMD, CPMD)
because of the high vibrational frequency of the H-bonds. If so, I can not
figure out how this can be specified in the dftb_in.hsd input. I tried both
the ways exposed in the manual, i.e.:

 

Masses {
Mass {
Atoms = 1:2
MassPerAtom [amu] = 2.0
}

}

 

and

 

Masses {
Mass {
Atoms = H
MassPerAtom [amu] = 2.0

}

}  

 

even if the latter one seems limited to the MODES input, but I always get an
error message.

Any advice is appreciated.

 

Thank you in advance.

Best,

Daniele Veclani.

 

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