Recently,the discovery of vanadium-based kagome metal AV_(3)Sb_(5)(A=K,Rb,Cs)has attracted great interest in the field of superconductivity due to the coexistence of superconductivity,non-trivial surface state and mul...Recently,the discovery of vanadium-based kagome metal AV_(3)Sb_(5)(A=K,Rb,Cs)has attracted great interest in the field of superconductivity due to the coexistence of superconductivity,non-trivial surface state and multiple density waves.In this topical review,we present recent works of superconductivity and unconventional density waves in vanadium-based kagome materials AV_(3)Sb_(5).We start with the unconventional charge density waves,which are thought to correlate to the time-reversal symmetry-breaking orders and the unconventional anomalous Hall effects in AV_(3)Sb_(5).Then we discuss the superconductivity and the topological band structure.Next,we review the competition between the superconductivity and charge density waves under different conditions of pressure,chemical doping,thickness,and strains.Finally,the experimental evidence of pseudogap pair density wave is discussed.展开更多
Based on classical density functional theory, an expression of the pressure tensor for inhomogeneous fluids is presented. This takes into account greater correlation between particles, especially for systems that are ...Based on classical density functional theory, an expression of the pressure tensor for inhomogeneous fluids is presented. This takes into account greater correlation between particles, especially for systems that are geometrically confined or involve an interface. The density and pressure components of Lennard-Jones fluids confined in hard and softened nano-cavities are calculated. A comparison between the results of this work and IK expression suggests that the agreement depends on temperature. The interracial tension for hard sphere fluids agrees well with the Monte Carlo result when the bulk density is not too large. The results of the solid fluid interracial tension for Lennard-Jones fluids demonstrate that different types of external potentials modulate the interfacial tension in different manners.展开更多
Bloch electrons in multiorbital systems carry quantum geometric information characteristic of their wavevector-dependent interorbital mixing.The geometric nature impacts electromagnetic responses,and this effect carri...Bloch electrons in multiorbital systems carry quantum geometric information characteristic of their wavevector-dependent interorbital mixing.The geometric nature impacts electromagnetic responses,and this effect carries over to the superconducting state,which receives a geometric contribution to the superfluid weight.In this paper,we show that this contribution could become negative under certain appropriate circumstances.This may facilitate the stabilization of Cooper pairings with real space phase modulation,i.e.,the pair density wave order,as we demonstrate through two-orbital model Bogoliubov de-Gennes mean-field calculations.The quantum geometric effect therefore constitutes an intrinsic mechanism for the formation of such a novel phase of matter in the absence of external magnetic field.展开更多
It has been demonstrated that intermolecular interaction,crucial in a plenty of chemical and physical processes,may vary in the presence of metal surface.However,such modification is yet to be quantitatively revealed....It has been demonstrated that intermolecular interaction,crucial in a plenty of chemical and physical processes,may vary in the presence of metal surface.However,such modification is yet to be quantitatively revealed.Here,we present a systematical density functional theory study on adsorbed bis(para-pyridyl)acetylene(BPPA) tetramer on Au(111) surface.We observed unusually high electron density between two head-to-head N atoms,an intermolecular "non-bonded" region,in adsorbed BPPA tetramer.This exceptional electron density originates from the wavefunction hybridization of the two compressed N lone-electron-pair states of two BPPA,as squeezed by a newly revealed N-Au-N threecenter bonding.This bond,together with the minor contribution from N...H-C intermolecular hydrogen bonding,shortens the N-N distance from over 4 A to 3.30 A and offers an attractive lateral interacting energy of 0.60 eV,effectively to a surface-confined in-plane pressure.The overlapped non-bonding vvavefunction hybridization arising from the effective pressure induced by the N-Au-N three-center bonding,as not been fully recognized in earlier studies,was manifested in non-contact Atomic Force Microscopy.展开更多
基金support from the Ministry of Science and Technology of Chinathe National Natural Science Foundation of China and Chinese Academy of Sciences
文摘Recently,the discovery of vanadium-based kagome metal AV_(3)Sb_(5)(A=K,Rb,Cs)has attracted great interest in the field of superconductivity due to the coexistence of superconductivity,non-trivial surface state and multiple density waves.In this topical review,we present recent works of superconductivity and unconventional density waves in vanadium-based kagome materials AV_(3)Sb_(5).We start with the unconventional charge density waves,which are thought to correlate to the time-reversal symmetry-breaking orders and the unconventional anomalous Hall effects in AV_(3)Sb_(5).Then we discuss the superconductivity and the topological band structure.Next,we review the competition between the superconductivity and charge density waves under different conditions of pressure,chemical doping,thickness,and strains.Finally,the experimental evidence of pseudogap pair density wave is discussed.
基金Project supported by the North China Electric Power University Campus Foundation (Grant No. 200911036)
文摘Based on classical density functional theory, an expression of the pressure tensor for inhomogeneous fluids is presented. This takes into account greater correlation between particles, especially for systems that are geometrically confined or involve an interface. The density and pressure components of Lennard-Jones fluids confined in hard and softened nano-cavities are calculated. A comparison between the results of this work and IK expression suggests that the agreement depends on temperature. The interracial tension for hard sphere fluids agrees well with the Monte Carlo result when the bulk density is not too large. The results of the solid fluid interracial tension for Lennard-Jones fluids demonstrate that different types of external potentials modulate the interfacial tension in different manners.
基金supported by the National Natural Science Foundation of China(Grant No.11904155)the Guangdong Provincial Key Laboratory(Grant No.2019B121203002)+1 种基金the Guangdong Science and Technology Department(Grant No.2022A1515011948)the Shenzhen Science and Technology Program(Grant No.KQTD20200820113010023)。
文摘Bloch electrons in multiorbital systems carry quantum geometric information characteristic of their wavevector-dependent interorbital mixing.The geometric nature impacts electromagnetic responses,and this effect carries over to the superconducting state,which receives a geometric contribution to the superfluid weight.In this paper,we show that this contribution could become negative under certain appropriate circumstances.This may facilitate the stabilization of Cooper pairings with real space phase modulation,i.e.,the pair density wave order,as we demonstrate through two-orbital model Bogoliubov de-Gennes mean-field calculations.The quantum geometric effect therefore constitutes an intrinsic mechanism for the formation of such a novel phase of matter in the absence of external magnetic field.
基金supported by the Ministry of Science and Technology(MOST)of China(Nos.2012CB932704,2012CB933001)the National Natural Science Foundation of China(NSFC,Nos.11274380,91433103,21173058,11622437,61674171 and 21203038)supported by the Outstanding Innovative Talents Cultivation Funded Programs 2015 of Renmin University of China
文摘It has been demonstrated that intermolecular interaction,crucial in a plenty of chemical and physical processes,may vary in the presence of metal surface.However,such modification is yet to be quantitatively revealed.Here,we present a systematical density functional theory study on adsorbed bis(para-pyridyl)acetylene(BPPA) tetramer on Au(111) surface.We observed unusually high electron density between two head-to-head N atoms,an intermolecular "non-bonded" region,in adsorbed BPPA tetramer.This exceptional electron density originates from the wavefunction hybridization of the two compressed N lone-electron-pair states of two BPPA,as squeezed by a newly revealed N-Au-N threecenter bonding.This bond,together with the minor contribution from N...H-C intermolecular hydrogen bonding,shortens the N-N distance from over 4 A to 3.30 A and offers an attractive lateral interacting energy of 0.60 eV,effectively to a surface-confined in-plane pressure.The overlapped non-bonding vvavefunction hybridization arising from the effective pressure induced by the N-Au-N three-center bonding,as not been fully recognized in earlier studies,was manifested in non-contact Atomic Force Microscopy.