Coordination of Mercury(II) in Water Promoted over Hydrolysis in Solvated Clusters [Hg(HO)]: Insights from Relativistic Effects and Free Energy Analysis.

Understanding the nature of the interaction between mercury(II) ions, Hg, and water molecules is crucial to describe the stability and chemical behavior of structures formed during solvation, as well as the conditions that favor the Hg coordination or inducing water hydrolysis. In our study, we explored exhaustively the potential energy surface of Hg with up to six water molecules. We analyzed electronic and Gibbs free energies, binding, and nuclear magnetic resonance parameters.

Relativistic quantum calculations to understand the contribution of f-type atomic orbitals and chemical bonding of actinides with organic ligands.

The nuclear waste problem is one of the main interests of rare earth and actinide element chemistry. Studies of actinide-containing compounds are at the frontier of the applications of current theoretical methods due to the need to consider relativistic effects and approximations to the Dirac equation in them. Here, we employ four-component relativistic quantum calculations and scalar approximations to understand the contribution of f-type atomic orbitals in the chemical bonding of actinides (Ac) to organic ligands.

The LRESC-Loc Model to Analyze Magnetic Shieldings with Localized Molecular Orbitals.

The leading electronic mechanisms of relativistic effects in the NMR magnetic shieldings of heavy-atom (HA) containing molecules are well described by the linear response with elimination of small components model (LRESC). We show here first results from a new version of the LRESC model written in terms of localized molecular orbitals (LMOs) which is coined as LRESC-Loc. Those LMOs resemble "chemist's orbitals", representing lone-pairs, atomic cores, and bonds.

Understanding the nature of bonding interactions in the carbonic acid dimers.

Carbonic acid dimer, (CA), (HCO), helps to explain the existence of this acid as a stable species, different to a simple sum between carbon dioxide and water. Five distinct, well characterized types of intermolecular interactions contribute to the stabilization of the dimers, namely, C=O⋯H-O, H-O⋯H-O, C=O⋯C=O, C=O⋯O-H, and C-O⋯O-H. In many cases, the stabilizing hydrogen bonds are of at least the same strength as in the water dimer.

Grid-based algorithm to search critical points, in the electron density, accelerated by graphics processing units.

Using a grid-based method to search the critical points in electron density, we show how to accelerate such a method with graphics processing units (GPUs). When the GPU implementation is contrasted with that used on central processing units (CPUs), we found a large difference between the time elapsed by both implementations: the smallest time is observed when GPUs are used. We tested two GPUs, one related with video games and other used for high-performance computing (HPC).