Question for calculation of water layer on Pt metal surfaces

Chanwoo Noh

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Oct 19, 2016, 10:26:41 PM10/19/16

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Dear all,

I have been studying to use CP2K program to perform the DFT calculations.

I have some questions whether input options and system size are adequate for my system, so please give me any comments or advices for my calculation options below.

My system for DFT calculation is a hydronium ion and water layer on the Pt(111) metal slab.

The Pt slab is described as 4 layers with 6*6 Pt atoms per each layer, and 23 water molecules and one hydronium ion are arranged on the platinum slab.

During the geometry optimization, below two layers of Pt are fixed, and other atoms are allowed to relax.

In addition, a vacuum of 6d, where d is the slab thickness of platinum, are added, so total box size is 16.75angstr *16.75angstr(60degrees) * 70angstr.

With above system, my input options are following:

The multigrid option is used with 500Ry grid cutoff, and 50Ry relative cutoff.

Total charge and multiplicity are set to 1.

The Fermi Dirac smear option is used for accelerate the SCF calculation, and broyden_mixing option is also used.

PBE functional is used for DFT functional.

DZVP-MOLOPT-SR-GTH basis is used for Pt atoms, and DZVP-MOLOPT-GTH basis are used for H and O atoms.

DFTd3 VdW potential is also used, for Van der Waals interaction is important for water system.

Are there any problems or something to be changed in my options?

I would be appreciate if you give me any comments for my question.

My input file is modified from the tutorial input file https://www.cp2k.org/howto:converging_cutoff, and my input and output files are attached as files.

Pt_H3O.out

Pt_H3O-pos-1.xyz

Pt_H3O.xyz

Pt_H3O.inp

Conrad

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Oct 20, 2016, 5:24:12 AM10/20/16

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Dear Chanwoo Noh,

It would also be useful to mention what the goal of your study is, and what chemistry you're interested in.

Best wishes,

Conrad

Chanwoo Noh

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Oct 20, 2016, 6:13:02 AM10/20/16

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Dear Conrad,

I am sorry that I missed to mention the important points you pointed out.

My goal of the study is to calculate the IR vibrational spectrum of hydronium ion and water on Pt(111) metal surface.

It is necessary to perform geometry optimization before calculating vibrational specturm, so I asked about calculating geometry optimization.

In addition to the system I mentioned above, I will also calculate the system in which the number of water layer is two or three, and I will compare the IR spectrum of those systems.