scholarly journals Structure and separation quality of various N- and O-donor ligands from quantum-chemical calculations

Nukleonika ◽  
2015 ◽  
Vol 60 (4) ◽  
pp. 847-851 ◽  
Author(s):  
Michael Trumm ◽  
Bernd Schimmelpfennig ◽  
Andreas Geist
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Donor Ligands ◽  
Field Development ◽  
Force Field Development ◽  
The Density Functional Theory ◽  
Complexation Reactions

Abstract Although BTP (2,6-di(1,2,4-triazin-3-yl)pyridine) has been proven to be a highly effective N-donor ligand for the selective An(III)/Ln(III) separation, the origin of its selectivity is still under discussion. We present in this paper quantum-chemical calculations at the density functional theory (DFT) and MP2 level which highlight the role of the aquo ions in the separation process. Furthermore these data will be the reference for future force-field development to investigate the differences in An(III) complexation reactions compared to their Ln(III) counterparts.

THE ROLE OF SUBSTRATE IN PACKING STRUCTURES OF SEXITHIOPHENES ON AG (111) SURFACE: MOLECULAR DYNAMICS SIMULATIONS AND QUANTUM CHEMICAL CALCULATIONS

2009 ◽  
Vol 08 (04) ◽  
pp. 677-690 ◽  
Author(s):  
JIN WEN ◽  
JING MA
Keyword(s):  
Molecular Dynamics ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Md Simulations ◽  
Site Preference ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Dynamics Simulations

Packing structures and orientation of sexithiophene (6T) molecules on Ag (111) surface are investigated by molecular dynamics (MD) simulations and quantum chemical calculations. Both the cluster and the slab models are employed. The density functional theory and molecular mechanism calculations demonstrate a weak physisorption and little site-preference in thiophene/ Ag (111) system. The MD simulations show that in the first layer close to the surface, the nearly coplanar 6T strips lie parallel with long axes deviating from [Formula: see text] direction about 20° – 30° and 75° – 90°. The average adsorption height of the monolayer is about 3.2 Å with most of the sulfur atoms in thienyl rings sitting on the bridge site of Ag (111) surface. The 6T molecules tend to take tilted orientations when they are far away from the surface. The packing structures of 6T layers deposited on the surface resulted from the competition between the molecule–substrate and intermolecular interactions.

Exploring the reducing role of boron: added insights from theory

2016 ◽  
Vol 45 (14) ◽  
pp. 5978-5988 ◽  
Author(s):  
Yuvraj Dangat ◽  
Kumar Vanka
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Functional Theory ◽  
Co Coupling ◽  
Full Quantum

Why are boron containing systems so effective at CO coupling? Full quantum chemical calculations with density functional theory (DFT) provide interesting insights into why recently reported CO coupling by diboryne systems is such a facile process.

Driving Torsion Scans with Wavefront Propagation

2020 ◽  
Author(s):  
Yudong Qiu ◽  
Daniel Smith ◽  
Chaya Stern ◽  
mudong feng ◽  
Lee-Ping Wang
Keyword(s):  
Potential Energy ◽  
Force Field ◽  
Degrees Of Freedom ◽  
Computational Cost ◽  
Initial Guess ◽  
Field Development ◽  
Force Field Development ◽  
Wavefront Propagation ◽  
Open Source Software Package

<div>The parameterization of torsional / dihedral angle potential energy terms is a crucial part of developing molecular mechanics force fields.</div><div>Quantum mechanical (QM) methods are often used to provide samples of the potential energy surface (PES) for fitting the empirical parameters in these force field terms.</div><div>To ensure that the sampled molecular configurations are thermodynamically feasible, constrained QM geometry optimizations are typically carried out, which relax the orthogonal degrees of freedom while fixing the target torsion angle(s) on a grid of values.</div><div>However, the quality of results and computational cost are affected by various factors on a non-trivial PES, such as dependence on the chosen scan direction and the lack of efficient approaches to integrate results started from multiple initial guesses.</div><div>In this paper we propose a systematic and versatile workflow called \textit{TorsionDrive} to generate energy-minimized structures on a grid of torsion constraints by means of a recursive wavefront propagation algorithm, which resolves the deficiencies of conventional scanning approaches and generates higher quality QM data for force field development.</div><div>The capabilities of our method are presented for multi-dimensional scans and multiple initial guess structures, and an integration with the MolSSI QCArchive distributed computing ecosystem is described.</div><div>The method is implemented in an open-source software package that is compatible with many QM software packages and energy minimization codes.</div>

scholarly journals Dynamics of Oxidation of Reduced Forms of CO2 under Electrochemical and Open-Сircuit Conditions on Polycrystalline Pt in H2CO3

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 274
Author(s):  
Alexander V. Smolin ◽  
Мikhail N. Mikhailov ◽  
Aleksey F. Gadzaov ◽  
Leonid M. Kustov
Keyword(s):  
Quantum Chemical ◽  
Preliminary Analysis ◽  
Oxidation Reaction ◽  
Density Functional ◽  
Oxidation Process ◽  
Open Circuit ◽  
Organic Substances ◽  
Oxidation Of Co ◽  
Reduced Forms

The problem of identifying correlations between catalytic and electrocatalytic processes is one of the fundamental problems of catalysis among “simple” organic substances, and the oxidation of CO and rCO2 is of great interest, since CO and CO2 are considered in pairs both during catalytic and electrocatalytic transformations. In the case of electrocatalysis, this analysis is important in the study of fuel cells. In this paper, we studied the correlation between the oxidation of reduced forms of CO2 (rCO2) under potentiodynamic-galvanoctatic electrochemical and open-circuit conditions of measurements on polycrystalline (pc)Pt in H2CO3. Periodic oscillations are revealed at the oxidation of Had and rCO2 on (pc)Pt. Quantum chemical calculations were carried out on the Pt13 cluster in order to identify the mechanisms of the rCO2 oxidation reaction. The correspondence in the energy parameters of the oxidation process of rCO2 under open-circuit conditions and electrochemical conditions is shown. The preliminary analysis of the system using density functional (DFT) calculations is carried out and the most stable systems that are based on Pt13 are found, namely rOH-Pt13-(CO)n, rOH-Pt13-(COH) and rOH-Pt13-(rCOOH). OH• species was chosen as the most likely candidate for the role of the oxidant for rCO2. Preliminary calculations for the expected reactions were carried out, and the optimal PES is revealed.

scholarly journals Role of redox-inactive metals in controlling the redox potential of heterometallic manganese–oxido clusters

2021 ◽  
Author(s):  
Keisuke Saito ◽  
Minesato Nakagawa ◽  
Manoj Mandal ◽  
Hiroshi Ishikita
Keyword(s):  
Photosystem Ii ◽  
Redox Potential ◽  
Quantum Chemical Calculations ◽  
Catalytic Reaction ◽  
Quantum Chemical ◽  
Ionic Radius ◽  
Redox Potentials ◽  
Oxygen Evolving ◽  
Highest Occupied Molecular Orbitals

AbstractPhotosystem II (PSII) contains Ca2+, which is essential to the oxygen-evolving activity of the catalytic Mn4CaO5 complex. Replacement of Ca2+ with other redox-inactive metals results in a loss/decrease of oxygen-evolving activity. To investigate the role of Ca2+ in this catalytic reaction, we investigate artificial Mn3[M]O2 clusters redox-inactive metals  [M] ([M]  = Mg2+, Ca2+, Zn2+, Sr2+, and Y3+), which were synthesized by Tsui et al. (Nat Chem 5:293, 2013). The experimentally measured redox potentials (Em) of these clusters are best described by the energy of their highest occupied molecular orbitals. Quantum chemical calculations showed that the valence of metals predominantly affects Em(MnIII/IV), whereas the ionic radius of metals affects Em(MnIII/IV) only slightly.

A density functional theory insight into the structure and reactivity of diphenyltin(IV) derivative of glycylphenylalanine

2016 ◽  
Vol 39 (3-4) ◽  
Author(s):  
Sandeep Pokharia ◽  
Rachana Joshi ◽  
Mamta Pokharia ◽  
Swatantra Kumar Yadav ◽  
Hirdyesh Mishra
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Functional Theory ◽  
Insight Into

AbstractThe quantum-chemical calculations based on density functional theory (DFT) have been performed on the diphenyltin(IV) derivative of glycyl-phenylalanine (H

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