New Insights from an Empirical Multi-Property Interatomic Potential and Predicted Collision-induced Light Scattering Spectra for Hg-rare Gas van der Waals Complexes

2016 ◽  
Vol 230 (1) ◽  
Author(s):  
Mohamed S. A. El-Kader ◽  
George Maroulis
Keyword(s):  
Light Scattering ◽  
Interatomic Potential ◽  
Mercury Vapor ◽  
Inert Gases ◽  
Van Der Waals Complexes ◽  
Rare Gas ◽  
Quantum Mechanical ◽  
Interatomic Potentials ◽  
Mechanical Methods ◽  
Scattering Spectra

AbstractAn empirical interatomic potentials for the interaction of Hg with inert gases are developed by simultaneously fitting the modified Tang–Toennies (MTT) potential function to spectroscopic data, thermo-physical and transport properties over a wide temperature range. The two-body anisotropic collision-induced light scattering spectra of mercury vapor with mixtures of rare gas has never been measured. The lineshape calculations through quantum mechanical methods have been used to predict a reasonable experimental spectra of the induced light scattering at

Computational methods for the study of energies of cation distributions: applications to cation-ordering phase transitions and solid solutions

2001 ◽  
Vol 65 (2) ◽  
pp. 193-219 ◽  
Author(s):  
A. Bosenick ◽  
M. T. Dove ◽  
E. R. Myers ◽  
E. J. Palin ◽  
C. I. Sainz-Diaz ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
Phase Transitions ◽  
Thermodynamic Properties ◽  
Quantum Mechanical ◽  
Cation Ordering ◽  
Interatomic Potentials ◽  
Cation Site ◽  
Mechanical Methods ◽  
Cation Distributions

AbstractThe structural and thermodynamic properties of minerals are strongly affected by cation site-ordering processes. We describe methods to determine the main interatomic interactions that drive the ordering process, which are based on parameterizing model Hamiltonians using empirical interatomic potentials and/or ab initio quantum mechanics methods. The methods are illustrated by a number of case study examples, including Al/Si ordering in aluminosilicates, Mg/Ca ordering in garnets, simultaneous Al/Si and Mg/Al ordering in pyroxenes, micas and amphiboles, and Mg/Al non-convergent ordering in spinel using only quantum mechanical methods.

Empirical Interatomic Potential from Polarized and Depolarized Interaction-Induced Light Scattering Spectra for Gaseous Helium

2002 ◽  
Vol 216 (10) ◽  
Author(s):  
Mohamed Sayed Abdel El-Kader
Keyword(s):  
Light Scattering ◽  
Room Temperature ◽  
Interatomic Potential ◽  
Reliable Determination ◽  
Gaseous Helium ◽  
Interatomic Separation ◽  
Scattering Spectra ◽  
First Time ◽  
Potential Parameters

Polarized and depolarized interaction-induced light scattering spectra at room temperature (294.5±1) K have been used for deriving the empirical multiparameter Morse–Morse–Morse–spline–van der Waals interatomic potential. These new data of scattering are accurate enough to permit for the first time a reliable determination of the interatomic potential of the gaseous helium as a function of the interatomic separation. The potential parameters describing the location and depth of the attractive well are given by ε = 11.2±0.015 K,

Empirical Interatomic Potential from Depolarized Interaction – Induced Light Scattering Spectra for Mercury

2001 ◽  
Vol 215 (7) ◽  
Author(s):  
M.S.A. Kader
Keyword(s):  
Light Scattering ◽  
Interatomic Potential ◽  
Theoretical Calculations ◽  
Second Moments ◽  
Scattering Spectra

Depolarized interaction-induced light scattering spectra of mercury between 793 K and 1073 K have been used for deriving the empirical multiparameter M3SV interatomic potential. Absolute zeroth and second moments have been measured and compared with theoretical calculations using various models for the interatomic potential. The results show that it is the most accurate potential yet reported for this system.

scholarly journals Interactions between large molecules pose a puzzle for reference quantum mechanical methods

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yasmine S. Al-Hamdani ◽  
Péter R. Nagy ◽  
Andrea Zen ◽  
Dennis Barton ◽  
Mihály Kállay ◽  
...  
Keyword(s):  
Experimental Information ◽  
Quantum Mechanical ◽  
Interaction Energies ◽  
Small Organic Molecules ◽  
Large Molecules ◽  
Reference Information ◽  
Mechanical Methods ◽  
Non Covalent Interactions ◽  
Semi Empirical ◽  
Covalent Interactions

AbstractQuantum-mechanical methods are used for understanding molecular interactions throughout the natural sciences. Quantum diffusion Monte Carlo (DMC) and coupled cluster with single, double, and perturbative triple excitations [CCSD(T)] are state-of-the-art trusted wavefunction methods that have been shown to yield accurate interaction energies for small organic molecules. These methods provide valuable reference information for widely-used semi-empirical and machine learning potentials, especially where experimental information is scarce. However, agreement for systems beyond small molecules is a crucial remaining milestone for cementing the benchmark accuracy of these methods. We show that CCSD(T) and DMC interaction energies are not consistent for a set of polarizable supramolecules. Whilst there is agreement for some of the complexes, in a few key systems disagreements of up to 8 kcal mol−1 remain. These findings thus indicate that more caution is required when aiming at reproducible non-covalent interactions between extended molecules.

scholarly journals A Review on Combination of Ab Initio Molecular Dynamics and NMR Parameters Calculations

2021 ◽  
Vol 22 (9) ◽  
pp. 4378
Author(s):  
Anna Helena Mazurek ◽  
Łukasz Szeleszczuk ◽  
Dariusz Maciej Pisklak
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Small Amplitude ◽  
Ab Initio Molecular Dynamics ◽  
Quantum Mechanical ◽  
Time Step ◽  
Noticeable Effect ◽  
Nmr Parameters ◽  
Mechanical Methods ◽  
Simulation Time

This review focuses on a combination of ab initio molecular dynamics (aiMD) and NMR parameters calculations using quantum mechanical methods. The advantages of such an approach in comparison to the commonly applied computations for the structures optimized at 0 K are presented. This article was designed as a convenient overview of the applied parameters such as the aiMD type, DFT functional, time step, or total simulation time, as well as examples of previously studied systems. From the analysis of the published works describing the applications of such combinations, it was concluded that including fast, small-amplitude motions through aiMD has a noticeable effect on the accuracy of NMR parameters calculations.

scholarly journals A transferable active-learning strategy for reactive molecular force fields

2021 ◽  
Author(s):  
Tom Young ◽  
Tristan Johnston-Wood ◽  
Volker L. Deringer ◽  
Fernanda Duarte
Keyword(s):  
Machine Learning ◽  
Active Learning ◽  
Learning Strategy ◽  
Force Fields ◽  
Molecular Simulations ◽  
Quantum Mechanical ◽  
Interatomic Potentials ◽  
Molecular Force ◽  
High Level ◽  
Active Learning Strategy

Predictive molecular simulations require fast, accurate and reactive interatomic potentials. Machine learning offers a promising approach to construct such potentials by fitting energies and forces to high-level quantum-mechanical data, but...

scholarly journals New Approach for Correcting Noncovalent Interactions in Semiempirical Quantum Mechanical Methods: The Importance of Multiple-Orientation Sampling

2021 ◽  
Vol 17 (9) ◽  
pp. 5556-5567
Author(s):  
Sergio Pérez-Tabero ◽  
Berta Fernández ◽  
Enrique M. Cabaleiro-Lago ◽  
Emilio Martínez-Núñez ◽  
Saulo A. Vázquez
Keyword(s):  
Noncovalent Interactions ◽  
Quantum Mechanical ◽  
New Approach ◽  
Mechanical Methods
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