Investigation on the pKa of Acids by Computational Simulation using the Density Functional Theory

Youze Fang

doi:10.6911/WSRJ.202512_11(12).0002

Authors

Youze Fang

DOI:

https://doi.org/10.6911/WSRJ.202512_11(12).0002

Keywords:

Density Functional Theory (DFT), Kohn–Sham formalism, pKa prediction, Aspartic acid, Chlorine-substituted ethanoic acid, Proton dissociation energy, Solvation modelling

Abstract

We present a Density Functional Theory (DFT) study to investigate the pKa values of various acids. A brief background on quantum mechanics is provided to introduce the fundamental principles of Kohn–Sham DFT. We then apply DFT to calculate the proton dissociation energies of chlorine-substituted ethanoic acid and aspartic acid. While the computed trends for chlorine-substituted ethanoic acid agree well with experimental observations, noticeable discrepancies arise in the case of aspartic acid. We further analyze and rationalize the underlying factors contributing to this divergence between theoretical predictions and experimental results.

Downloads

Download data is not yet available.

References

[1] Kohn, W., & Sham, L. J. (1965). Self-consistent equations including exchange and correlation effects. Physical Review, 140(4A), A1133–A1138. https://doi.org/10.1103/PhysRev.140.A1133

[2] Parr, R. G., & Yang, W. (1994). Density-Functional Theory of Atoms and Molecules. Oxford University Press.

[3] Becke, A. D. (1993). Density‐functional thermochemistry. III. The role of exact exchange. The Journal of Chemical Physics, 98(7), 5648–5652. https://doi.org/10.1063/1.464913

[4] Hehre, W. J., Ditchfield, R., & Pople, J. A. (1972). Self-consistent molecular orbital methods. XII. Further extensions of Gaussian-type basis sets for use in molecular orbital studies of organic molecules. The Journal of Chemical Physics, 56(5), 2257–2261. https://doi.org/10.1063/1.1677527

[5] Ditchfield, R., Hehre, W. J., & Pople, J. A. (1971). Self-consistent molecular-orbital methods. IX. An extended Gaussian-type basis for molecular-orbital studies of organic molecules. The Journal of Chemical Physics, 54(2), 724–728. https://doi.org/10.1063/1.1674902