Vibrational Properties of the Isotopomers of the Water Dimer Derived from Experiment and Computations

2014 ◽  
Vol 67 (3) ◽  
pp. 426 ◽  
Author(s):  
Robert Kalescky ◽  
Wenli Zou ◽  
Elfi Kraka ◽  
Dieter Cremer
Keyword(s):  
Binding Energy ◽  
Zero Point ◽  
Binding Energies ◽  
Water Dimer ◽  
General Observation ◽  
Reduced Pressure ◽  
Point Energy ◽  
Deuterium Substitution ◽  
Mass Increase

The water dimer and its 11 deuterated isotopomers are investigated utilizing coupled cluster theory and experimental data as input for a perturbational determination of the isotopomer frequencies. Deuterium substitution reduces the H-bond stretching frequency by maximally 12 cm–1 from 143 to 131 cm–1, which makes a spectroscopic differentiation of H- and D-bonds difficult. However, utilizing the 132 frequencies obtained in this work, the identification of all isotopomers is straightforward. The CCSD(T)/CBS value of the binding energy De is 5.00 kcal mol–1. The binding energy D0 of the water dimer increases upon deuterium substitution from 3.28 to maximally 3.71 kcal mol–1 reflecting a decrease in the zero point energy contribution. The entropy values of the D-isotopomers increase from 73 to 77 entropy units in line with the general observation that a mass increase leads to larger entropies. All 12 isotopomers possess positive free binding energies at 80 K and a reduced pressure of 110 Pa, which means that they can be spectroscopically observed under these conditions.

scholarly journals ON DETERMINATION OF THE GEOMETRIC COSMOLOGICAL CONSTANT FROM THE OPERA EXPERIMENT OF SUPERLUMINAL NEUTRINOS

2012 ◽  
Vol 27 (11) ◽  
pp. 1250041 ◽  
Author(s):  
MU-LIN YAN ◽  
SEN HU ◽  
WEI HUANG ◽  
NENG-CHAO XIAO
Keyword(s):  
Dark Energy ◽  
Cosmological Constant ◽  
Fundamental Constant ◽  
Zero Point ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Point Energy ◽  
Sitter Spacetime ◽  
Effective Cosmological Constant

The recent OPERA experiment of superluminal neutrinos has deep consequences in cosmology. In cosmology a fundamental constant is the cosmological constant. From observations one can estimate the effective cosmological constant Λ eff which is the sum of the quantum zero point energy Λ dark energy and the geometric cosmological constant Λ. The OPERA experiment can be applied to determine the geometric cosmological constant Λ. It is the first study to distinguish the contributions of Λ and Λ dark energy from each other by experiment. The determination is based on an explanation of the OPERA experiment in the framework of Special Relativity with de Sitter spacetime symmetry.

STRUCTURAL, ELECTRONIC, AND OPTICAL PROPERTIES OF ZnxSy (x + y = 2 TO 4) NANOCLUSTERS: A B3LYP-DFT STUDY

2011 ◽  
Vol 10 (01n02) ◽  
pp. 341-344
Author(s):  
P. S. YADAV ◽  
D. K. PANDEY ◽  
S. AGRAWAL ◽  
B. K. AGRAWAL
Keyword(s):  
Optical Properties ◽  
Visible Region ◽  
Zero Point ◽  
Binding Energies ◽  
Ultraviolet Region ◽  
Point Energy ◽  
Electronic And Optical Properties ◽  
The Stability ◽  
The One ◽  
Homo Lumo

The stability, structural, electronic, and optical properties have been studied for most stable zinc sulfide nanoclusters Zn x S y (x + y = n = 2 to 4). A B3LYP-DFT/6-311G(3df) method is employed to optimize the geometries, and a TDDFT method is used for the study of the optical properties. The binding energies (BE), HOMO–LUMO gaps and the bond lengths have been obtained for all the clusters. We have considered also the zero point energy (ZPE) corrections ignored by the earlier workers. For a fixed value of n, we designate the most stable structure the one, which has maximum final binding energy per atom. The adiabatic and vertical ionization potentials (IP) and electron affinities (EA), charge on atoms, dipole moment, and optical properties have been investigated for the most stable structures. The nanoclusters containing large number of S atoms for each "n" are found to be most stable. Except for ZnS nanocluster, the HOMO–LUMO gap increases with the number of S atoms. Similarly, except for ZnS , IP and EA fluctuate with the cluster size but reveal downward trend. The optical absorption is quite weak in visible region but is strong in the ultraviolet region in most of the nanoclusters except a few. The growth of most stable nanoclusters may be possible in the experiments.

scholarly journals A Hessian free method to prevent zero-point energy leakage in classical trajectory simulation

2022 ◽  
Author(s):  
Saikat Mukherjee ◽  
Mario Barbatti
Keyword(s):  
Degrees Of Freedom ◽  
Zero Point ◽  
Classical Trajectory ◽  
The Other ◽  
Water Dimer ◽  
Dynamics Simulation ◽  
Zero Point Energy ◽  
Point Energy ◽  
Quantum Uncertainty ◽  
Local Vibrational Mode

The problem associated with the zero-point energy (ZPE) leak in classical trajectory calculations is well known. Since ZPE is a manifestation of the quantum uncertainty principle, there are no restrictions on energy during the classical propagation of nuclei. This phenomenon can lead to unphysical results, such as forming products without the ZPE in the internal vibrational degrees of freedom (DOFs). The ZPE leakage also permits reactions below the quantum threshold for the reaction. We have developed a new Hessian-free method, inspired by the Lowe-Andersen thermostat model, to prevent energy dipping below a threshold in the local-pair (LP) vibrational DOFs. The idea is to pump the leaked energy to the corresponding local vibrational mode, taken from the other vibrational DOFs. We have applied the new correction protocol on the ab initio ground-state molecular dynamics simulation of the water dimer (H20)2, which dissociates due to unphysical ZPE spilling from the high-frequency OH modes. The LP-ZPE method has been able to prevent the ZPE spilling of the OH stretching modes by pumping back the leaked energy into the corresponding modes while this energy is taken from the other modes of the dimer itself, keeping the system as a microcanonical ensemble.

scholarly journals Non-equilibrium Binding Energy Determined Using Alpha-amylase Catalysed Amylolysis of Gelatinised Starch as a Probable Generalisable Model and Importance

2020 ◽  
pp. 9-23
Author(s):  
Ikechukwu I. Udema
Keyword(s):  
Binding Energy ◽  
Thermal Energy ◽  
Enzyme Assay ◽  
Substrate Inhibition ◽  
Binding Energies ◽  
Binding Interaction ◽  
Enzyme Substrate ◽  
Equilibrium Binding ◽  
Non Equilibrium

Objectives: This research was undertaken to determine the non–equilibrium binding energy by calculation after substituting experimental data into derived equations, present its role distinct from energy associated with activated enzyme–substrate (ES) complex and ultimately elucidate the importance of binding energies. Background: There are overwhelming pieces of evidence in the literature that binding interaction is essential for the ultimate transformation of a substrate, inhibition of vital enzymes of pathogens, covid-19 in particular. Intrinsic binding energy herein referred to as non–equilibrium binding energy and energy associated with activated ES are seen to be chemical in origin. Much attention seemed not to be given to theoretical approach to the determination of non–equilibrium binding energy. Methods: Experimental approach (Bernfeld method of enzyme assay) and calculational. Results and Discussion: The non–equilibrium translational (2.691–2.726 kJ/mol) and total electrostatic energies (2.755-3.154 kJ/mol) were > than the thermal energy at 310.15 k. The interfacial distance between the bullet and target molecule was expectedly very short; the range was between 6.672 and 7.570 exp (- 12) m. This was attributed to the interaction between charged enzyme and weakly polar substrate. Conclusion: The equations of non–equilibrium and translational energies were derivable. The binding interaction serves to fix the bullet molecule on or into the target (supra) molecule before the commencement of transition state formation. The non–equilibrium binding interactions of the bullet (drugs, substrate, etc) and target (receptors e.g. enzymes, pathogens such as Covid–19, Plasmodium etc) and the ultimate complex are likely to be stabilised against the thermal energy in furtherance of enzymatic and drug action since the electrostatic interaction energy is higher than thermal energy.

scholarly journals Determination of Descriptors Which Influence the Toxicity of Organochlorine Compounds Using Qsar Method

2019 ◽  
pp. 1-13 ◽  
Author(s):  
Massapihanhoro Ouattara Pierre ◽  
Bamba Kafoumba ◽  
N’guessan Nobel Kouakou ◽  
Ziao Nahossé
Keyword(s):  
Poecilia Reticulata ◽  
Principal Component ◽  
Zero Point ◽  
Organochlorine Compounds ◽  
Test Set ◽  
Point Energy ◽  
Physicochemical Descriptors ◽  
The Family ◽  
Qsar Models

Organochlorine Pesticides (OCP) are organic compounds obtained by the chlorination of various unsaturated hydrocarbons. They are very toxic and therefore belong to the family of persistent organic pollutants. If formerly these pesticides were used to fight against certain vectors of diseases and thus improve the productivity of the host, today they are considered as "enemy" of the environment. To understand the origin of the toxicity of organochlorine compounds, we used 73 molecules (test set: 50 and validation: 23) containing at least one chlorine atom and for which the toxicity (LogLC50) against Poecilia reticulata is known to establish QSAR models. Firstly, we used principal component analysis (PCA) to identify the best descriptors. Then, the different models were established using the method of multiple linear regression (MLR). Models established with quantum and physicochemical descriptors only showed satisfactory results. But the best model was determined with the combination of both quantum and physicochemical descriptors. The criteria of this model are as follows: R2 = 0.939 ; R2ajusted = 0.932 ; Pvalue < 0.0001; α = 0.05 R2CV = 0.935 ; R2 - R2CV = 0.004 ; MCE = 0.073; F = 134.701 These criteria show that the toxicity of organochlorine compounds is well described by the combination of quantum and physicochemical descriptors namely lipophilia (LogP), polarizability (pol), entropy (S), zero-point energy (ZPE) and the number of chlorine atoms (NCl).

Evaluation of Ar tagging toward the vibrational spectra and zero point energy of X-HOH, X-DOH, and X-HOD, for X=F, Cl, Br

2021 ◽  
Author(s):  
Wikorn Puniyan ◽  
Kaito Takahashi
Keyword(s):  
Binding Energy ◽  
Vibrational Spectra ◽  
Zero Point ◽  
Zero Point Energy ◽  
Halide Anion ◽  
Point Energy ◽  
Anion Complexes

In this study, we theoretically evaluated the effect of argon tagging toward the binding energy and vibrational spectra of water halide anion complexes, Ar.X-HOH, Ar.X-HOD, and Ar.X-DOH (X=F, Cl, Br)....

Sign in / Sign up

Export Citation Format

Share Document