Density functional theory (DFT) has since long established itself as the standard theory to calculate many properties of matter from first principles, and to give insight and rationalize experimental results. The popularity of DFT is mostly due to its Kohn-Sham approximation method that occupies a "sweet spot" at the intersection of accuracy and computational cost. As a first approximation, one can model any charge transfer process as a modification of the occupation of Kohn-Sham orbitals in a static point of view. Indeed, following this idea, the calculated electronic properties of thiol-protected gold clusters have been successfully used to model charge transfer processes in electrochemistry [1,2]. However, when more complex systems and processes are involved, or when higher accuracy and level of prediction is required, one needs to devise a strategy that identifies the shortcomings and strengths of every available method and optimizes the accuracy/CPU time ratio by combining different approaches. Motivated by the study of amorphous carbon (a-C) electrodes to measure concentrations of neurotransmitters in the human brain, we performed simulations aiming at understanding the charge transfer process between the a-C electrode and the biomolecule using an efficient combination of Kohn-Sham DFT, hybrid-functional DFT and classical molecular dynamics, among other approaches. This ranges from generating the a-C network that makes up the electrode material [3], to describing the water/electrode interface [4], to predicting redox potentials for the molecules of interest. [1] K. A Kacprzak, L. Lehtovaara, J. Akola, O. Lopez-Acevedo, H. Häkkinen. "A density functional investigation of thiolate-protected bimetal PdAu24(SR)18z clusters" PCCP 11 (33), 7123-7129 (2009) [2] JF Parker, KA Kacprzak, O Lopez-Acevedo, H Häkkinen, RW Murray "Experimental and density functional theory analysis of serial introductions of electron-withdrawing ligands into the ligand shell of a thiolate-protected Au25 nanoparticle" J Phys Chem C 114 (18), 8276-8281 (2010) [3] M. A. Caro, R. Zoubkoff, O. Lopez-Acevedo, and T. Laurila, "Atomic and electronic structure of tetrahedral amorphous carbon surfaces from density functional theory: Properties and simulation strategies", Carbon 77, 1168 (2014) [4] M. A. Caro, J. Määtta, O. Lopez-Acevedo, and T. Laurila, "Energy band alignment and electronic states of amorphous carbon surfaces in vacuo and in aqueous environment", J. Appl. Phys. 117, 034502 (2015)

Improving the accuracy of DFT modeling of electrochemistry

251st National Meeting (2016)

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