Density corrected SCAN functional in water clusters

The main hurdle of Kohn-Sham Density Functional Theory (DFT)[1,2] is finding the exact exchange-correlation contribution to energy.?The accuracy of practical DFT depends not only on the choice of density functional approximations but also on the electron density produced by approximations. SCAN[3] (Strongly Constrained and Appropriately Normed) is the first meta-GGA (meta generalized gradient approximation) constrained to obey all 17 known exact constraints that a meta-GGA can. SCAN has been found to outperform most other functionals when applied to aqueous systems[4]. However, density driven errors (energy errors occurring from applying a DFA to its inexact self-consistent density) hinder SCAN from achieving chemical accuracy in some systems, including water. Density-corrected DFT (HF-DFT) alleviates this shortcoming using a more accurate electron density.?We calculated binding energies of different water clusters using Density-corrected SCAN (DC-SCAN) and find them remarkably close to reference values calculated at the CCSD(T) level of theory[5,6,7].

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[4] L. Zheng, M. Chen, Z. Sun, H. –Y. Ko, B. Santra, P. Dhuvad, and X. Wu , J. Chem. Phys. 148, 164505 (2018)

[5] E . Lambros , S. Dasgupta , E. Palos, S. Swee, J. Hu, F. Paesani , J. Chem. Theory Comput. 17, 5635-5650 (2021)

[6] S. Dasgupta, E. Lambros, J. P. Perdew, and F. Paesani , Nat. Commun. 12, 1-12 (2021)

[7] S. Dasgupta , C. Shahi, P. Bhetwal, J. P. Perdew, and F. Paesani, J. Chem. Theory Comput. 18, 4745-4761 (2022)