Based on the three-coupled-oscillator molecular model we proposed, the relation between the second-order susceptibilities of a chiral film and the molecular hyperpolarizabilities is given. The effect of microscopic pa...Based on the three-coupled-oscillator molecular model we proposed, the relation between the second-order susceptibilities of a chiral film and the molecular hyperpolarizabilities is given. The effect of microscopic parameters on the second-order susceptibilities is simulated numerically and the difference between the efficiencies of s-polarized secondharmonic fields induced by the left- and the right-handed circularly-polarized fundamental beams is discussed. The theoretical basis for studying second-order nonlinear optical properties of the chiral molecular media with a tripod-like structure is provided in this paper.展开更多
A novel variational approach is proposed to calculate the ground-state (GS) properties of the two-site Holstein model. By the linear superposition of two coherent states, which simulate the behaviour of the weak and...A novel variational approach is proposed to calculate the ground-state (GS) properties of the two-site Holstein model. By the linear superposition of two coherent states, which simulate the behaviour of the weak and strong coupling limits, we can obtain very accurate GS energy for arbitrary electron-phonon coupling constant. Other GS properties are also discussed. Moreover, the present concise approach is hopefully generalized to many other Holstein models.展开更多
The Hückel’s rule,Baird’s rule,and electronic shell closure model are classical and well-established concepts in chemistry,which have long been employed in rationalizing the aromaticity/antiaromaticity of organ...The Hückel’s rule,Baird’s rule,and electronic shell closure model are classical and well-established concepts in chemistry,which have long been employed in rationalizing the aromaticity/antiaromaticity of organic species and stability of inorganic clusters.Thus,the observation of unique species featuring properties out of the fundamental frameworks of these rules is challenging but significant and helps in drawing a complete picture of fascinating concepts in chemistry.展开更多
An approximate calculation of the exchange interaction constant J_(RT)between the rare-earth sublattice and the transition metal sublattice in R_2Fe_(17-x)Al_x (R= Tb,Gd, and Dy) compounds is given by the molecular-fi...An approximate calculation of the exchange interaction constant J_(RT)between the rare-earth sublattice and the transition metal sublattice in R_2Fe_(17-x)Al_x (R= Tb,Gd, and Dy) compounds is given by the molecular-field model and the results of neutron diffraction.The calculated values, -J_(R,T)/k, for Dy_2Fe_(17-x)Al_x (x=5, 6, 7 and 8), Tb_2Fe_(10)Al_7,Gd_2Fe_(17-x)Al_x (x=7, 8) compounds are 8.62K, 8.64K, 9.52K, 10.34K and 10.66K, 10.65K, and 9.85K,respectively, they are in agreement with the experimental values, -J_(R,T)/k, of Dy_2Fe_(17-x)Al_x(x=5, 6, 7 and 8), Tb_2Fe_(10)Al_7 and Gd_2Fe_(17-x)Al_x (x=7, 8) compounds, which are 8.77K, 9.25K,10.1K, 10.9K and 10.35K, 10.1K, and 10.3K, respectively. The origins of the difference between thecalculated and the experimental results are discussed.展开更多
While studying the electrophilic cyclization of acetylenic malonates in synthesizing malonate indene derivatives with high regio and stereo-selectivity, we found that the CH2 and CH3 protons of two COOCH2CH3 groups in...While studying the electrophilic cyclization of acetylenic malonates in synthesizing malonate indene derivatives with high regio and stereo-selectivity, we found that the CH2 and CH3 protons of two COOCH2CH3 groups in some diethyl malonate indene derivatives showed very interesting spin-spin coupling and signal multiplicity. To explain those phenomena, we synthesized several diethyl malonate indene derivatives, and then used 1H NMR spectra and molecular modeling to investigate the CH2CH3 spin system of these two COOCH2CH3 groups in detail. The results showed that the spin systems of CH3CH2 of the two COOCH2CH3 groups in those compounds may exist in different froms (AMX3, ABX3 and A2X3), and the effect of the aromatic ring induced by the phenyl group at the end of the triple bond is the main reason responsible for those phenomena.展开更多
Exploring the mechanism of interfacial thermal transport and reducing the interfacial thermal resistance are of great importance for thermal management and modulation.Herein,the interfacial thermal resistance between ...Exploring the mechanism of interfacial thermal transport and reducing the interfacial thermal resistance are of great importance for thermal management and modulation.Herein,the interfacial thermal resistance between overlapped graphene nanoribbons is largely reduced by adding bonded carbon chains as shown by molecular dynamics simulations.And the analytical model(phonon weak couplings model,PWCM)is utilized to analyze and explain the two-dimensional thermal transport mechanism at the cross-interface.An order of magnitude reduction of the interfacial thermal resistance is found as the graphene nanoribbons are bonded by just one carbon chain.Interestingly,the decreasing rate of the interfacial thermal resistance slows down gradually with the increasing number of carbon chains,which can be explained by the proposed theoretical relationship based on analytical model.Moreover,by the comparison of PWCM and the traditional simplified model,the accuracy of PWCM is demonstrated in the overlapped graphene nanoribbons.This work provides a new way to improve the interfacial thermal transport and reveal the essential mechanism for low-dimensional materials applied in thermal management.展开更多
基金Project supported by the Natural Science Foundation of Heilongjiang Province, China (Grant No A200406).
文摘Based on the three-coupled-oscillator molecular model we proposed, the relation between the second-order susceptibilities of a chiral film and the molecular hyperpolarizabilities is given. The effect of microscopic parameters on the second-order susceptibilities is simulated numerically and the difference between the efficiencies of s-polarized secondharmonic fields induced by the left- and the right-handed circularly-polarized fundamental beams is discussed. The theoretical basis for studying second-order nonlinear optical properties of the chiral molecular media with a tripod-like structure is provided in this paper.
基金Supported by the National Natural Science Foundation of China under Grant Nos 19804009 and 10274067.
文摘A novel variational approach is proposed to calculate the ground-state (GS) properties of the two-site Holstein model. By the linear superposition of two coherent states, which simulate the behaviour of the weak and strong coupling limits, we can obtain very accurate GS energy for arbitrary electron-phonon coupling constant. Other GS properties are also discussed. Moreover, the present concise approach is hopefully generalized to many other Holstein models.
基金supported by the Taishan Scholars Project of Shandong Province(no.ts201712011)the National Natural Science Foundation of China(NSFC)(nos.21603119 and 21705093)+4 种基金the Natural Science Foundation of Shandong Province(nos.ZR2017BB061 and ZR2016BQ09)the Natural Science Foundation of Jiangsu Province(no.BK20170396)the Project for Scientific Research Innovation Team of Young Scholar in Colleges and Universities of Shandong Province(no.2019KJC025)the Young Scholars Program of Shandong University(YSPSDU)(no.2018WLJH48)the Qilu Youth Scholar Funding of Shandong University,and the Fundamental Research Funds of Shandong University(no.2017TB003).
文摘The Hückel’s rule,Baird’s rule,and electronic shell closure model are classical and well-established concepts in chemistry,which have long been employed in rationalizing the aromaticity/antiaromaticity of organic species and stability of inorganic clusters.Thus,the observation of unique species featuring properties out of the fundamental frameworks of these rules is challenging but significant and helps in drawing a complete picture of fascinating concepts in chemistry.
基金This work was supported by the Research Fund of Hebei Education Committee(Grant No.2001108).
文摘An approximate calculation of the exchange interaction constant J_(RT)between the rare-earth sublattice and the transition metal sublattice in R_2Fe_(17-x)Al_x (R= Tb,Gd, and Dy) compounds is given by the molecular-field model and the results of neutron diffraction.The calculated values, -J_(R,T)/k, for Dy_2Fe_(17-x)Al_x (x=5, 6, 7 and 8), Tb_2Fe_(10)Al_7,Gd_2Fe_(17-x)Al_x (x=7, 8) compounds are 8.62K, 8.64K, 9.52K, 10.34K and 10.66K, 10.65K, and 9.85K,respectively, they are in agreement with the experimental values, -J_(R,T)/k, of Dy_2Fe_(17-x)Al_x(x=5, 6, 7 and 8), Tb_2Fe_(10)Al_7 and Gd_2Fe_(17-x)Al_x (x=7, 8) compounds, which are 8.77K, 9.25K,10.1K, 10.9K and 10.35K, 10.1K, and 10.3K, respectively. The origins of the difference between thecalculated and the experimental results are discussed.
文摘While studying the electrophilic cyclization of acetylenic malonates in synthesizing malonate indene derivatives with high regio and stereo-selectivity, we found that the CH2 and CH3 protons of two COOCH2CH3 groups in some diethyl malonate indene derivatives showed very interesting spin-spin coupling and signal multiplicity. To explain those phenomena, we synthesized several diethyl malonate indene derivatives, and then used 1H NMR spectra and molecular modeling to investigate the CH2CH3 spin system of these two COOCH2CH3 groups in detail. The results showed that the spin systems of CH3CH2 of the two COOCH2CH3 groups in those compounds may exist in different froms (AMX3, ABX3 and A2X3), and the effect of the aromatic ring induced by the phenyl group at the end of the triple bond is the main reason responsible for those phenomena.
基金Project supported by the National Natural Science Foundation of China(Grant No.51606072)the Fundamental Research Funds for the Central Universities,HUST,China(Grant No.2019kfyRCPY045)。
文摘Exploring the mechanism of interfacial thermal transport and reducing the interfacial thermal resistance are of great importance for thermal management and modulation.Herein,the interfacial thermal resistance between overlapped graphene nanoribbons is largely reduced by adding bonded carbon chains as shown by molecular dynamics simulations.And the analytical model(phonon weak couplings model,PWCM)is utilized to analyze and explain the two-dimensional thermal transport mechanism at the cross-interface.An order of magnitude reduction of the interfacial thermal resistance is found as the graphene nanoribbons are bonded by just one carbon chain.Interestingly,the decreasing rate of the interfacial thermal resistance slows down gradually with the increasing number of carbon chains,which can be explained by the proposed theoretical relationship based on analytical model.Moreover,by the comparison of PWCM and the traditional simplified model,the accuracy of PWCM is demonstrated in the overlapped graphene nanoribbons.This work provides a new way to improve the interfacial thermal transport and reveal the essential mechanism for low-dimensional materials applied in thermal management.