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979 results on '"Fang, Wei‐Hai"'

53. Unveiling Mechanistic Insights and Photocatalytic Advancements in Intramolecular Photo-(3 + 2)-Cycloaddition: A Comparative Assessment of Two Paradigmatic Single-Electron-Transfer Models

Author

Wang, Chu, Liu, Xiao, Wang, Qian, Fang, Wei-Hai, and Chen, Xuebo

Abstract

The synthesis of 1-aminonorbornane (1-aminoNB), a potential aniline bioisostere, through photochemistry or photoredox catalysis signifies a remarkable breakthrough with implications in organic chemistry, pharmaceutical chemistry, and sustainable chemistry. However, an understanding of the underlying mechanisms involved in these reactions remains limited and ambiguous. Herein, we employ high-precision CASPT2//CASSCF calculations to elucidate the intricate mechanisms regulating the intramolecular photo-(3 + 2)-cycloaddition reactions for the synthesis of 1-aminoNB in the presence or absence of the Ir-complex-based photocatalyst. Our investigations delve into radical cascades, stereoselectivity, particularly single-electron-transfer (SET) events, etc. Furthermore, we innovatively introduce and compare two SET models integrating Marcus electron-transfer theory and transition-state theory. These models combined with kinetic data contribute to recognizing the critical control factors in diverse photocatalysis, thereby guiding the design and manipulation of photoredox catalysis as well as the improvement and modification of photocatalysts.

Published
2024
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54. Distributed Multi-GPU Ab InitioDensity Matrix Renormalization Group Algorithm with Applications to the P-Cluster of Nitrogenase

Author

Xiang, Chunyang, Jia, Weile, Fang, Wei-Hai, and Li, Zhendong

Abstract

The presence of many degenerate d/f orbitals makes polynuclear transition-metal compounds, such as iron–sulfur clusters in nitrogenase, challenging for state-of-the-art quantum chemistry methods. To address this challenge, we present the first distributed multi-graphics processing unit (GPU) ab initiodensity matrix renormalization group (DMRG) algorithm suitable for modern high-performance computing (HPC) infrastructures. The central idea is to parallelize the most computationally intensive part─the multiplication of O(K2) operators with a trial wave function, where Kis the number of spatial orbitals, by combining operator parallelism for distributing the workload with a batched algorithm for performing contractions on GPU. With this new implementation, we are able to reach an unprecedentedly large bond dimension D= 14,000 on 48 GPUs (NVIDIA A100 80 GB SXM) for an active space model (114 electrons in 73 active orbitals) of the P-cluster, which is nearly 3 times larger than the bond dimensions reported in previous DMRG calculations for the same system using only central processing units (CPUs).

Published
2024
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69. Photo-dissociation mechanism of trifluoroacetyl chloride in the gas phase: AIMS dynamic simulations.

Author

Hao, Yuxia, Liu, Lihong, and Fang, Wei-Hai

Subjects
HYDROGEN chloride, DYNAMIC simulation, AB-initio calculations
Abstract

In this article, the structures and energies of CF3COCl in the low-lying electronic states have been determined by SA-2-CAS(8,7)/6-31G* and SA-2-MSPT2(8,7)/6-31G* calculations, which include equilibrium geometries, transition states, and three minimum-energy conical intersections (CI-1, CI-2, and CI-3) between S0 and S1 states. The AIMS method was used to carry out non-adiabatic dynamic simulations with the ab initio calculation performed at the SA-2-CAS(8,7)/6-31G* level. Upon irradiation to the S1 state, CF3COCl first relaxes to S1 minimum and then overcomes the ∼10 kcal/mol (TSS1_CCl) or ∼30 kcal/mol (TSS1_CO) barrier to the conical intersection region CI-1 or CI-3 (minor), with the S1 → S0 transition probability of 63:1. After non-adiabatic transition to the S0 state through CI-1, trajectories mainly distribute to three different reaction pathways, with one going back to S0 minimum through shortening of the C–Cl bond, the other forming CF3CO and Cl radicals by continuous elongation of the C–Cl distance, and another dissociating into CF3 + CO + Cl and running into the CI-3 region through elongation of C–C and C–Cl distances. Moreover, we found that the trajectories would recross to the S1 state with the recrossing probability of 13.9% through the CI-3 region due to the extremely sloped topographic character of CI-3. On the basis of time evolution of wavefunctions simulated here, the product ratio of CF3 + CO + Cl and CF3CO + Cl is 53.5%:18.4%, which is consistent with the experimental value of 3:1. We further explain the photo-dissociation wavelength dependence of CF3COCl, and the product ratio of CF3 + CO + Cl increases with the increase in total energy. [ABSTRACT FROM AUTHOR]

Published
2021
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72. Aromaticity Concerto in Polycyclic Conjugated Hydrocarbons: Fusion Pattern on Combined Aromaticity Strategy Leads to Distinctive Excited State Photophysics of Dinaphthopentalenes

Author

Wang, Long, primary, Lin, Lu, additional, Zhang, Teng-Shuo, additional, Guo, Shaoting, additional, Liu, Zuyuan, additional, Zhang, Mengfan, additional, Wang, Senhao, additional, Cui, Ganglong, additional, Fang, Wei-Hai, additional, Zhu, Jun, additional, Fu, Hongbing, additional, and Yao, Jiannian, additional

Published
2022
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79. Influence of tungsten doping on nonradiative electron–hole recombination in monolayer MoSe2 with Se vacancies.

Author

Yang, Yating, Tokina, Marina V., Fang, Wei-Hai, Long, Run, and Prezhdo, Oleg V.

Subjects
ELECTRON-hole recombination, CHARGE carrier lifetime, TIME-dependent density functional theory, ION recombination, CHARGE carriers, TUNGSTEN
Abstract

Two-dimensional transition metal dichalcogenides (TMDs) are receiving significant attention due to their excellent electronic and optoelectronic properties. The material quality is greatly affected by defects that are inevitably generated during material synthesis. Focusing on chalcogenide vacancies, which constitute the most common defect, we use the state-of-the-art simulation methodology developed in our group to demonstrate that W doping of MoSe2 with Se vacancies reduces charge carrier losses by two mechanisms. First, W doping makes the formation of double Se vacancies unfavorable, while it is favorable in undoped MoSe2. Second, if a Se vacancy is present, the charge carrier lifetimes are extended in the W-doped MoSe2. Combining ab initio real-time time-dependent density functional theory with nonadiabatic molecular dynamics, the simulations show that the nonradiative carrier losses in the presence of Se vacancies proceed by sub-10 ps electron trapping and relaxation down the manifold of trap states, followed by a 100 ps recombination of trapped electrons with free holes. The electron–vibrational energy exchange is driven by both in-plane and out-of-plane vibrational motions of the MoSe2 layer. The atomistic studies advance our understanding of the influence of defects on charge carrier properties in TMDs and guide improvements of material quality and development of TMD applications. [ABSTRACT FROM AUTHOR]

Published
2020
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80. Variational Quantum Computation of Molecular Linear Response Properties on a Superconducting Quantum Processor

Author

Huang, Kaixuan, primary, Cai, Xiaoxia, additional, Li, Hao, additional, Ge, Zi-Yong, additional, Hou, Ruijuan, additional, Li, Hekang, additional, Liu, Tong, additional, Shi, Yunhao, additional, Chen, Chitong, additional, Zheng, Dongning, additional, Xu, Kai, additional, Liu, Zhi-Bo, additional, Li, Zhendong, additional, Fan, Heng, additional, and Fang, Wei-Hai, additional

Published
2022
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