# CP2K Open Source Molecular Dynamics

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exercises:common:wf

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 exercises:common:wf [2022/10/31 18:11] – removed jglan exercises:common:wf [2022/10/31 18:12] (current) – old revision restored (2022/09/20 15:06) jglan Both sides previous revisionPrevious revision2022/10/31 18:12 jglan old revision restored (2022/09/20 15:06)2022/10/31 18:11 jglan removed2022/09/20 15:06 jglan 2022/09/20 15:05 jglan 2022/09/20 15:02 jglan 2022/09/20 15:00 jglan 2022/09/20 14:59 jglan 2022/09/20 14:59 jglan 2022/09/20 14:59 jglan 2022/09/20 14:59 jglan 2022/09/20 14:58 jglan created 2022/10/31 18:12 jglan old revision restored (2022/09/20 15:06)2022/10/31 18:11 jglan removed2022/09/20 15:06 jglan 2022/09/20 15:05 jglan 2022/09/20 15:02 jglan 2022/09/20 15:00 jglan 2022/09/20 14:59 jglan 2022/09/20 14:59 jglan 2022/09/20 14:59 jglan 2022/09/20 14:59 jglan 2022/09/20 14:58 jglan created Line 1: Line 1: + The **work function** is the minimum thermodynamic work needed to remove an electron from a solid (or surface) to a point in the vacuum. The work function is not a characteristic of a bulk material, but rather a property of the surface of the material. + The work function //W// for a given surface is defined by the difference between Fermi level and electrostatic potential in the vacuum: + + $W = -e\phi - E_f$ + + where $\phi$ is the electrostatic potential in the vacuum and $E_f$ is the Fermi level of the surface. + + Those two quantities can be obtained from [[https://manual.cp2k.org/cp2k-2022_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/PRINT/PDOS.html| PDOS]] and [[https://manual.cp2k.org/cp2k-2022_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/PRINT/V_HARTREE_CUBE.html | V_HARTREE_CUBE]]. + + One can use [[https://www.cp2k.org/tools:cubecruncher | Cubecruncher]] to compute the profile along the normal of the surface to obtained the electrostatic potential of the given surface and vacuum. + + + cubecruncher.x -i input.cube -o output.cube -1d_profile 3 0.001 +