Search results for " Computational Chemistry"
showing 8 items of 28 documents
Through-space spin-spin coupling in acetylenic systems. Ab initio and DFT calculations
2003
Abstract: We have investigated, by means of ab initio and DFT calculations, the magnitude of through-space spin-spin couplings ( J CH and J HH ) in CH/π bonded van der Waals dimers involving acetylene, and in a structurally related covalent compound (4-ethynylphenanthrene). Within regions where the interaction is stabilizing J HH couplings are very small (< 0.1 Hz) for all complexes. In the acetylene-methane complex J CH is also very small, whereas in the acetylene-benzene complex and the acetylene dimer it shows a relatively large dependence on the tilt angle from the T-shaped arrangement, for which the smallest values are calculated, to a parallel slipped arrangement where J CH is ca. 0.5…
The Effect of Calcium on the Cohesive Strength and Flexural Properties of Low-Methoxyl Pectin Biopolymers.
2019
Abstract: Pectin binds the mesothelial glycocalyx of visceral organs, suggesting its potential role as a mesothelial sealant. To assess the mechanical properties of pectin films, we compared pectin films with a less than 50% degree of methyl esterification (low-methoxyl pectin, LMP) to films with greater than 50% methyl esterification (high-methoxyl pectin, HMP). LMP and HMP polymers were prepared by step-wise dissolution and high-shear mixing. Both LMP and HMP films demonstrated a comparable clear appearance. Fracture mechanics demonstrated that the LMP films had a lower burst strength than HMP films at a variety of calcium concentrations and hydration states. The water content also influe…
OpenMolcas: From Source Code to Insight
2019
In this article we describe the OpenMolcas environment and invite the computational chemistry community to collaborate. The open-source project already includes a large number of new developments realized during the transition from the commercial MOLCAS product to the open-source platform. The paper initially describes the technical details of the new software development platform. This is followed by brief presentations of many new methods, implementations, and features of the OpenMolcas program suite. These developments include novel wave function methods such as stochastic complete active space self-consistent field, density matrix renormalization group (DMRG) methods, and hybrid multico…
Theoretical and experimental studies of some main group compounds : from closed shell interactions to singlet diradicals and stable radicals
2012
Acquiring knowledge of different interactions within and between molecules is a fascinating undertaking as it not only deepens our understanding of chemical bonding but also offers insight into electronic structures, molecular properties and the connections between these two. This dissertation combines together three main group chemistry related topics within the aforementioned theme. Research presented in the first third of this dissertation describes wave function and density functional theory studies of weak inter- and intramolecular interactions in pnictogen-based dimers X3Pn···PnX3 (Pn = N-Bi; X = F-I), dithallenes RTlTlR (R = H, Me, tBu, Ph) and octachalcogen dications Ch82+ (Ch = S, …
Molecular mechanics models for the image charge, a comment on “including image charge effects in the molecular dynamics simulations of molecules on m…
2017
We re-investigate the image charge model of Iori and Corni (Iori and Corni, J. Comput. Chem. 2008, 29, 1656). We find that a simple symmetrization of their model allows to obtain quantitatively correct results for the electrostatic interaction of a water molecule with a metallic surface. This symmetrization reduces the magnitude of the electrostatic interaction to less than 10% of the total interaction energy. © 2017 Wiley Periodicals, Inc.
Rapid self-healing and anion selectivity in metallosupramolecular gels assisted by fluorine-fluorine interactions.
2017
Simple ML2 [M = Fe(II), Co(II), Ni(II)] complexes obtained from a perfluoroalkylamide derivative of 4-aminophenyl-2,2′,6,2′-terpyridine spontaneously, yet anion selectively, self-assemble into gels, which manifest an unprecedented rapid gel strength recovery, viz. self-healing, and thermal rearrangement in aqueous dimethyl sulfoxide. The key factor for gelation and rheological properties emerges from the fluorine–fluorine interactions between the perfluorinated chains, as the corresponding hydrocarbon derivative did not form metallogels. The perfluoro-terpyridine ligand alone formed single crystals, while its Fe(II), Co(II) or Ni(II) complexes underwent rapid gelation leading to highly enta…
Structure ofD-ribonic acid-dimethyltin(IV) in coordinating solvents: an experimental and DFT119Sn NMR study
2006
We have investigated a newly synthesized complex of D-ribonic acid with dimethyltin(IV). The structure of the complex in solution has been characterized by means of 1 H, 13 C, and 119 Sn NMR and by DFT calculations. The comparison of experimental and computational results allowed the determination of the stable conformation in solution as well as the detection of a dimerization process. Moreover, evidence is given of active coordination of the metal by the solvent.
Computational studies on systems derived from barium zirconate perovskite structure
2010
In solid oxide protonic conductors, proton diffusion is mainly driven by phonon-assisted dynamics, for this, becoming important local distorsion studies on the lattice, in order to detail the protonic conduction mechanism hence to improve performances of the related materials. Here, the protonic conductor Y:BaZrO3 was studied by means of DFT calculations, using new tetravalent substitution models.