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979 results on '"Fang, Wei‐Hai"'

163. Photodissociation of HN3 at 248 nm and longer wavelength: a CASSCF study

Author

Fang, Wei-Hai

Subjects
Molecular dynamics -- Research, Chemicals, plastics and rubber industries
Abstract

The complete active space SCF method has been used to fully optimize the potential energy surfaces controlling hydrazoic acid dissociation to HN + N2 and H + N3 in the ground, excited triplet and singlet states. This research gives an insight into the mechanism of the ultraviolet protodissociation of HN3 at a wavelength range from 355 nm to 248 nm.

Published
2000

169. A CASSCF study on photodissociation of acrolein in the gas phase

Author

Fang, Wei-Hai

Subjects
Aldehydes -- Analysis, Carbonyl compounds -- Analysis, Chemical reactions -- Analysis, Dissociation -- Analysis, Scission (Chemistry) -- Analysis, Chemistry
Abstract

A study performed extensive CASSCF energy gradient ab initio calculations to obtain detailed information about the ground- and excited-state reaction paths of acrolein (CH2CHCHO) to characterize the mechanisms of its photodissociation. A large basis set was used to trace, at different levels, the ground- and excited-state potential energy profiles governing the CH2CHCHO dissociation to CH3CH+CO, CH2CH+ CHO and CH2CHCO + H. Results are discussed.

Published
1999

170. Theoretical characterization of the structures and reactivity of 7-hydroxyquinoline-(H2O)(sub n) (n = 1-3) complexes

Author

Fang, Wei-Hai

Subjects
Complex compounds -- Spectra, Aromatic compounds, Protons -- Research, Chemicals, plastics and rubber industries
Abstract

Research was conducted to examine the characterize the minimum-energy structure of the 7-hydroxyquinoline (7HQ)-(H2O)(sub n) (n = 1-3) complexes and the potential energy surfaces governing triple proton transfer in 7HQ-(H2O)2 and quadruple proton transfer in 7HQ-(H2O)3 using different ab initio quantum mechanical methods. The calculated results and experimental data were compared where available.

Published
1999

174. Tuning excited-state-intramolecular-proton-transfer (ESIPT) process and emission by cocrystal formation: a combined experimental and theoretical study† †Electronic supplementary information (ESI) available: Experimental details, characterization of cocrystals, and computational details and results. CCDC 1454754 and 1454755. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6sc04354b Click here for additional data file. Click here for additional data file

Author

Lin, Heyang, Chang, Xueping, Yan, Dongpeng, Fang, Wei-Hai, and Cui, Ganglong

Subjects
Chemistry
Abstract

The formation of two-component molecular cocrystals can lead to the tunable excited state intramolecular proton transfer (ESIPT) process and emission, as first confirmed by both experimental and computational studies.

Published
2016

176. Ab initio study of the triple-proton-transfer reactions of ground and excited states of 7-hydroxyquinoline in methanol solution

Author

Fang, Wei-Hai

Subjects
Methanol -- Usage, Protons -- Scattering, Chemistry
Abstract

Research was conducted to examine triple-proton-transfer reactions of ground and excited states of 7-hydroxyquinoline (7HQ) in methanol solution using different ab initio quantum mechanical calculations. The Onsager self-consistent reaction field model was used to include the solvent effects on the structures and potential energy profiles of the reactions. Analysis of the CIS and CASSCF results elucidated the main properties of the absorption and emission spectra related to the ground and the first excited states of 7HQ.

Published
1998

178. CO Adsorbate Promotes Polaron Photoactivity on the Reduced Rutile TiO2(110) Surface

Author

Cheng, Cheng, Zhu, Yonghao, Fang, Wei-Hai, Long, Run, and Prezhdo, Oleg V.

Abstract

Polarons play a major role in determining the chemical properties of transition-metal oxides. Recent experiments show that adsorbates can attract inner polarons to surface sites. These findings require an atomistic understanding of the adsorbate influence on polaron dynamics and lifetime. We consider reduced rutile TiO2(110) with an oxygen vacancy as a prototypical surface and a CO molecule as a classic probe and perform ab initioadiabatic molecular dynamics, time-domain density functional theory, and nonadiabatic molecular dynamics simulations. The simulations show that subsurface polarons have little influence on CO adsorption and CO can desorb easily. On the contrary, surface polarons strongly enhance CO adsorption. At the same time, the adsorbed CO attracts polarons to the surface, allowing them to participate in catalytic processes with CO. The CO interaction with polarons changes their orbital origin, suppresses polaron hopping, and stabilizes them at surface sites. Partial delocalization of polarons onto CO decouples them from free holes, decreasing the nonadiabatic coupling and shortening the quantum coherence time, thereby reducing charge recombination. The calculations demonstrate that CO prefers to adsorb at the next-nearest-neighbor five-coordinated Ti3+surface electron polaron sites. The reported results provide a fundamental understanding of the influence of electron polarons on the initial stage of reactant adsorption and the effect of the adsorbate–polaron interaction on the polaron dynamics and lifetime. The study demonstrates how charge and polaron properties can be controlled by adsorbed species, allowing one to design high-performance transition-metal oxide catalysts.

Published
2022
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