[Lammps]Flexible spc water vacf and spectrum

LAMMPS LAMMPS General Discussion
1

Dear all

I am try to simulate bulk liquid water using SPC/fw water model(SPC/Fw model of water page on SklogWiki - a wiki for statistical mechanics and thermodynamics). I would like to reproduce the IR spectrum of bulk liquid water by taking fast fourier transform of the velocity autocorrelation function.However, my spectrum doesn’t match with literature results for spc/fw water. The bond-strech peak position is 5100 cm^-1, which shift around 1500 cm^-1 from 3400 cm^-1.

could you please help me by telling me that is there anything wrong with my input file?

Thanks.
Best regards
Jiang

My result:
Spectrum-water-lammps
literature:

spectrum-SPCFw
spectrum-SPCFw864×882 119 KB

in.spce_bulk_harmonic (1.2 KB)
FlexibleH2O.txt (367 Bytes)

2

Have you discussed this with your adviser, tutor, or more experienced colleagues?
Please keep in mind an online forum is not a suitable replacement for that and that people can mostly tell glaringly obvious mistakes from your input, not so much bad choices or bad planning.

Please also note that this is a forum about using LAMMPS, but not a place for discussing how to do proper research. Sometimes these two are difficult to separate but that is not the case here.

3

Thank you for your reply!.I understand.