Effect of the Solute Cavity on the Solvation Energy and its Derivatives within the Framework of the Gaussian Charge Scheme

Abstract

The treatment of the solvation charges using Gaussian functions in the polarizable continuum model results in a smooth potential energy surface. These charges are placed on top of the surface of the solute cavity. In this article, we study the effect of the solute cavity (van der Waals‐type or solvent‐excluded surface‐type) using the Gaussian charge scheme within the framework of the conductor‐like polarizable continuum model on (a) the accuracy and computational cost of the self‐consistent field (SCF) energy and its gradient and on (b) the calculation of free energies of solvation. For that purpose, we have considered a large set of systems ranging from few atoms to more than 200 atoms in different solvents. Our results at the DFT level using the B3LYP functional and the def2‐TZVP basis set show that the choice of the solute cavity does neither affect the accuracy nor the cost of calculations for small systems (< 100 atoms). For larger systems, the use of a vdW‐type cavity is recommended, as it prevents small oscillations in the gradient (present when using a SES‐type cavity), which affect the convergence of the SCF energy gradient. Regarding the free energies of solvation, we consider a solvent‐dependent probe sphere to construct the solvent‐accessible surface area required to calculate the nonelectrostatic contribution to the free energy of solvation. For this part, our results for a large set of organic molecules in different solvents agree with available experimental data with an accuracy lower than 1 kcal/mol for both polar and nonpolar solvents.

Quantum Mechanics/Molecular Mechanics Study of Resting-State Vanadium Nitrogenase: Molecular and Electronic Structure of the Iron–Vanadium Cofactor

“… a Using a Gaussian charge scheme and a scaled van der Waals surface. 101 b An additional two protons are added to cap residues 423 His and 257 Cys . c The RMSD is defined as the deviation of the [VFe 7 S 8 C(XO 3 )] part with respect to both cofactors in the crystal structure.…”

The importance of finite temperature and vibrational sampling in the absorption spectrum of a nitro-functionalized Ru(ii) water oxidation catalyst

“…Further, the calculations used the RIJCOSX [32][33][34] approximation for computational efficiency 35 together with the SARC/J 36,37 auxiliary basis set. Solvent effects (acetonitrile, MeCN) were taken into account in the optimizations using the C-PCM Gaussian charge scheme 38,39 continuum solvation model. Frequency calculations showed that the optimized structures correspond to minima (no imaginary frequency).…”

Dielectric continuum methods for quantum chemistry

“…The SwiG implementation of PCMs first appeared in the Q‐ Chem program, 241 and was extended recently to discretize not only the vdW and SAS cavities but also the SES 25 . Related discretization schemes have since been adopted in other software 242,243 . While alternative discretization methods have been described subsequently, 244–247 it is unclear whether these have been formulated with gradients in mind.…”

“…25 Related discretization schemes have since been adopted in other software. 242,243 While alternative discretization methods have been described subsequently, [244][245][246][247] it is unclear whether these have been formulated with gradients in mind. Given the simplicity and success of the SwiG approach, it is also unclear what is to be gained from these formulations.…”