Why DFT‐Based Tight Binding Gives a Better Representation of the Potential at Metal‐Solution Interfaces than DFT Does

• DOI: 10.1002/celc.202300230
• Publication Date: 2023-09-26T10:41:43Z
• Authors: Paola Quaino; José Luis Nuñez; Bálint Aradi; Tammo van der Heide; Elizabeth Santos; Wolfgang Schmickler
• Keywords: Chemistry; tight binding; Industrial electrochemistry; 0103 physical sciences; work function; inner potential; potential of zero charge; DFT; QD1-999; 01 natural sciences; TP250-261

AbstractIn modelling electrochemical interfaces it is important to treat electrode and electrolyte at the same level of theory. Density functional theory, which is usually the method of choice, suffers from a distinct disadvantage: The inner potential is calculated as the average of the total electrostatic potential. This includes the highly localized potential generated from the nuclei. The resulting inner potential is far too high, of the order of 3.5 V, and not relevant for electrochemistry. In the density functional based tight binding (DFTB) method the electrostatic potential is much smoother, as it stems from atomic charge fluctuations with respect to neutral reference atoms. The resulting values for the electrochemical inner potential are much lower and compare well with those obtained by other, elaborate methods. Thus DFTB recommends itself as a method for treating the electrochemical interface including the inner potential.