(Ro)vibrational Spectroscopic Constants, Lifetime and QTAIM Evaluation of Fullerene Dimers Stability.

The iconic caged shape of fullerenes gives rise to a series of unique chemical and physical properties; hence a deeper understanding of the attractive and repulsive forces between two buckyballs can bring detrimental information about the structural stability of such complexes, providing significant data applicable for several studies. The potential energy curves for the interaction of multiple van der Waals buckyball complexes with increasing mass were theoretically obtained within the DFT framework at ωB97xD/6-31G(d) compound model. These potential energy curves were employed to estimate the spectroscopic constants and the lifetime of the fullerene complexes with the Discrete Variable Representation and with the Dunham approaches.

Theoretical Model of Polarization Effects on Third-Order NLO Properties of the Stilbazolium Derivative Crystal.

The linear and nonlinear properties of the stilbazolium derivative, 2-[2-(3-hydroxy-4-methoxy-phenyl)-vinyl]-1-methyl-pyridinium naphthalene-2-sulfonate dihydrate crystal (VSNS), were investigated using an iterative electrostatic embedding scheme and density functional theory (DFT). The dipole moment and second hyperpolarizability of the VSNS molecule are sharply influenced by its crystalline phase. Standard DFT global hybrids such as B3LYP and M06 are strongly benefited by the effects of crystalline polarization.

Theoretical study of the interaction of fullerenes with the emerging contaminant carbamazepine for detection in aqueous environments.

The global increase in drug consumption exposes the growing need to develop new systems for the detection, capture, and treatment of bioactive molecules. Carbamazepine is one instance of such contaminants at the top of the ranking commonly found in sewage treatment systems. This work, therefore, presents a theoretical study of fullerene C and its derivatives with substitutional doping with B, Al, Ga, Si, Ge, N and P, for the detection and capture of carbamazepine is aqueous medium.

Harnessing Greenhouse Gases Absorption by Doped Fullerenes with Externally Oriented Electric Field.

In this work, a theoretical investigation of the effects caused by the doping of C with silicon (Si) atom as well as the adsorption of CO, CO and N gases to C and CSi fullerenes was carried out. In concordance with previous studies, it was found that the choice of the doping site can control the structural, electronic, and energetic characteristics of the CSi system. The ability of C and CSi to adsorb CO, CO and N gas molecules was evaluated.

Explicit Aqueous Solvation Treatment of Epinephrine from Car-Parrinello Molecular Dynamics: Effect of Hydrogen Bonding on the Electronic Absorption Spectrum.

The electronic absorption spectrum of the neurotransmitter epinephrine (EPN) in water solution is studied, combining ab initio Car-Parrinello molecular dynamics (CPMD) with a quantum mechanical approach within the framework of the time-dependent density functional theory (TDDFT) scheme. By selecting 52 uncorrelated snapshots, the excitation modes were calculated at the LC-ωPBE/6-31+G(d) level of theory, using an optimal range-separation parameter ω, determined by means of the gap-tuning scheme in the presence of the solvent molecules. By comparing with static approaches (vacuum and implicit solvation), we show here that explicit solvation treatment dramatically enhances the photophysical properties of the EPN, especially because of the more realistic dynamic description of the molecular geometry.

Bond Ellipticity Alternation: An Accurate Descriptor of the Nonlinear Optical Properties of π-Conjugated Chromophores.

Well-defined structure-property relationships offer a conceptual basis to afford a priori design principles to develop novel π-conjugated molecular and polymer materials for nonlinear optical (NLO) applications. Here, we introduce the bond ellipticity alternation (BEA) as a robust parameter to assess the NLO characteristics of organic chromophores and illustrate its effectiveness in the case of streptocyanines. BEA is based on the symmetry of the electron density, a physical observable that can be determined from experimental X-ray electron densities or from quantum-chemical calculations.