[CP2K:8585] imaginary frequencies of water dimer even with tight convergence parameters

Ali KACHMAR ali.kac... at gmail.com
Wed Jan 25 17:35:33 UTC 2017

Dear Luis,

1. a cutoff of 400 Ry is a bit low for geometry optimization + vibrational
frequency calculations on water systems. Please run your geometry
optimization with tight convergence and a cutoff=550 Ry, Relcutoff=70 Ry

2. Starting from the optimized geometry, please run your vibrational
analysis calculation using a DX=0.01, and add to the GEO_OPT section


All the best,

On Tue, Jan 24, 2017 at 6:00 PM, <lar... at lbl.gov> wrote:

> I am trying to compute the vibrational frequencies of small water
> clusters, and I am having trouble getting rid of imaginary frequencies,
> even for the water dimer, using very tight convergence parameters during
> the geometry optimization.I have also tried to run the simulations with
> periodic boundary conditions, different values of the displacement, etc.,
> but I still get a few imaginary frequencies. I have run out of ideas to try
> so any advice will be greatly appreciated. I have attached here the input
> files of the calculations.
> Thanks for your time!
> Luis
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