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456 results on '"Wang, Meishan"'

1. Non-adiabatic dynamics studies of the C+(2P1/2, 3/2) + H2 reaction: Based on global diabatic potential energy surfaces of CH2+.

Author

Li, Wentao, Dong, Bin, Niu, Xianghong, Wang, Meishan, and Zhang, Yong

Subjects
POTENTIAL energy surfaces, DIFFERENTIAL cross sections, AB-initio calculations, WAVE packets, PROBABILITY theory
Abstract

Global diabatic potential energy surfaces (PESs) of CH2+ are constructed using the neural network method with a specific function based on 18 213 ab initio points. The multi-reference configuration interaction method with the aug-cc-pVQZ basis set is adopted to perform the ab initio calculations. The topographical properties of the diabatic PESs are examined in detail. In general, the diabatic PESs provide an accurate quasi-diabatic representation. To validate the diabatic PESs, the dynamics studies of the C+(2P1/2, 3/2) + H2 (v0 = 0, j0 = 0) → H + CH+(X1Σ+) reaction are performed using the time-dependent wave packet method. The reaction probabilities, integral cross sections, differential cross sections, and rate constants are calculated and compared with the experimental and theoretical results. Non-adiabatic dynamics results are in good agreement with experimental data. In addition, the non-adiabatic effect in the C+(2P1/2, 3/2) + H2 reaction is significant due to the non-adiabatic results being obviously larger than adiabatic values. The reasonable non-adiabatic dynamics results indicate that present diabatic PESs can be recommended for any type of dynamics study. [ABSTRACT FROM AUTHOR]

Published
2024
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4. An alternative indicator of annihilated electrons in atoms: Rahm's electronegativity scale

Author

Wu, Yu, Ma, Xiaoguang, Yuan, Fang, Sui, Jipeng, Wang, Meishan, and Yang, Chuanlu

Subjects
Physics - Atomic and Molecular Clusters
Abstract

This paper presents a new explanation of the width of gamma-ray spectra based on Rahm's electronegativity scale. This quantitatively proves, for the first time, that positrophilic electrons in the positron-electron annihilation process are exactly the valence electrons. This suggests the replacement of Full Width at Half Maximum (FWHM) of the gamma-ray spectra with the newly defined physical quantity Average Doppler Shift (ADS). Both FWHM and ADS of the gamma-ray spectra in light elements agree well with the corresponding Rahm's electronegativity values, respectively. Further, ADS provides strong evidence in favor of Rahm's electronegativity scale. It is expected that this will be useful in understanding the mechanism of the positron-electron annihilation process.

Published
2020
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5. Gamma -ray spectra in the positron-annihilation process of molecules at room temperature

Author

Tang, Lin, Ma, Xiaoguang, Sui, Jipeng, Wang, Meishan, and Yang, Chuanlu

Subjects
Physics - Atomic and Molecular Clusters
Abstract

In this study, a fully self-consistent method was developed to obtain the wave functions of the positron and electrons in molecules simultaneously. The wave function of a positron at room temperature , with a characteristic energy of approximately $0.04 eV$, was used to analyse the experimental results of its annihilation in helium, neon, hydrogen, and methane molecules. The interactions between the positron and molecule provide a significant correction in the gamma-ray spectra of the annihilating electron--positron pairs. It was also observed that high-order correlations offered almost no correction in the spectra, as the interaction between the low-energy positron and electrons cannot drive the electrons into excited electronic states. More accurate studies, which consider the coupling of the positron--electron pair states and vibration states of nuclei, must be undertaken.

Published
2020
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36. Theoretical Prediction of Electrocatalytic Reduction of CO2 Using a 2D Catalyst Composed of 3 d Transition Metal and Hexaamine Dipyrazino Quinoxaline.

Author

Zeng, Xianshi, Liao, Luliang, Yu, Qiming, Wang, Meishan, and Wang, Hongming

Subjects
ZINC catalysts, QUINOXALINES, COPPER, CATALYST testing, CATALYSTS, METAL-organic frameworks, TRANSITION metals, TRANSITION metal oxides
Abstract

Transition metals and organic ligands combine to form metal‐organic frameworks (MOFs), which possess distinct active sites, large specific surface areas and stable porous structures, giving them considerable promise for CO2 reduction electrocatalysis. In the present study, using spin polarisation density‐functional theory, a series of 2D MOFs constructed from 3d transition metal and hexamethylene dipyrazoline quinoxaline(HADQ) were investigated. The calculated binding energies between HADQ and metal atoms for the ten TM‐HADQ monolayers were strong sufficient to stably disperse the metal atoms in the HADQ monolayers. Of the ten catalysts tested, seven (Sc, Ni, Cu, Zn, Ti, V and Cr) exhibited high CO2 reduction selectivity, while Mn, Fe and Co required pH values above 2.350, 6.461 and 6.363, respectively, to exhibit CO2 reduction selectivity. HCOOH was the most important producer for Sc, Zn, Ni and Mn, while CH4 was the main producer for Ti, Cr, Fe and V. Cu and Co were less selective, producing HCHO, CH3OH, and CH4 simultaneously at the same rate‐determining step and limiting potential. The Cu‐HADQ catalyst had a high overpotential for the HCHO product (1.022 V), while the other catalysts had lower overpotentials between 0.016 V and 0.792 V. Thus, these results predict TM‐HADQ to show excellent activity in CO2 electrocatalytic reduction and to become a promising electrocatalyst for CO2 reduction. [ABSTRACT FROM AUTHOR]

Published
2023
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