scholarly journals Impact of nuclear vibrations on van der Waals and Casimir interactions at zero and finite temperature

2019 ◽  
Vol 5 (11) ◽  
pp. eaaw0456 ◽  
Author(s):  
Prashanth S. Venkataram ◽  
Jan Hermann ◽  
Teerit J. Vongkovit ◽  
Alexandre Tkatchenko ◽  
Alejandro W. Rodriguez
Keyword(s):  
Long Range ◽  
Van Der Waals ◽  
Power Laws ◽  
Molecular Structures ◽  
Molecular Response ◽  
Electromagnetic Interactions ◽  
Electronic Delocalization ◽  
Casimir Interactions ◽  
Low Dimensional ◽  
Vdw Interaction

Recent advances in measuring van der Waals (vdW) interactions have probed forces on molecules at nanometric separations from metal surfaces and demonstrated the importance of infrared nonlocal polarization response and temperature effects, yet predictive theories for these systems remain lacking. We present a theoretical framework for computing vdW interactions among molecular structures, accounting for geometry, short-range electronic delocalization, dissipation, and collective nuclear vibrations (phonons) at atomic scales, along with long-range electromagnetic interactions in arbitrary macroscopic environments. We primarily consider experimentally relevant low-dimensional carbon allotropes, including fullerenes, carbyne, and graphene, and find that phonons couple strongly with long-range electromagnetic fields depending on molecular dimensionality and dissipation, especially at nanometric scales, creating delocalized phonon polaritons that substantially modify infrared molecular response. These polaritons, in turn, alter vdW interaction energies between molecular and macroscopic structures, producing nonmonotonic power laws and nontrivial temperature variations at nanometric separations feasible in current experiments.

scholarly journals Controlling the anisotropy of a van der Waals antiferromagnet with light

2021 ◽  
Vol 7 (23) ◽  
pp. eabf3096
Author(s):  
Dmytro Afanasiev ◽  
Jorrit R. Hortensius ◽  
Mattias Matthiesen ◽  
Samuel Mañas-Valero ◽  
Makars Šiškins ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Long Range ◽  
Van Der Waals ◽  
Ultrashort Pulses ◽  
Anisotropy Axis ◽  
Two Dimensional ◽  
Orbital Symmetry ◽  
Nickel Ions ◽  
Long Range Correlations ◽  
Low Dimensional

Van der Waals magnets provide an ideal playground to explore the fundamentals of low-dimensional magnetism and open opportunities for ultrathin spin-processing devices. The Mermin-Wagner theorem dictates that as in reduced dimensions isotropic spin interactions cannot retain long-range correlations, the long-range spin order is stabilized by magnetic anisotropy. Here, using ultrashort pulses of light, we control magnetic anisotropy in the two-dimensional van der Waals antiferromagnet NiPS3. Tuning the photon energy in resonance with an orbital transition between crystal field split levels of the nickel ions, we demonstrate the selective activation of a subterahertz magnon mode with markedly two-dimensional behavior. The pump polarization control of the magnon amplitude confirms that the activation is governed by the photoinduced magnetic anisotropy axis emerging in response to photoexcitation of ground state electrons to states with a lower orbital symmetry. Our results establish pumping of orbital resonances as a promising route for manipulating magnetic order in low-dimensional (anti)ferromagnets.

Van der Waals Epitaxy of GaSe on GaAs(111)

1994 ◽  
Vol 340 ◽  
Author(s):  
L. E. Rumaner ◽  
F.S. Ohuchi
Keyword(s):  
Lattice Mismatch ◽  
Van Der Waals ◽  
Three Dimensional ◽  
Structured Materials ◽  
Lattice Matching ◽  
Molecular Beam Deposition ◽  
Crystal Films ◽  
Low Dimensional ◽  
Matching Constraints ◽  
Lattice Matched

ABSTRACTAlthough heteroepitaxy of lattice-matched and lattice-mismatched materials leading to artificially structured materials has resulted in impressive performance in various electronics devices, material combinations are usually limited by lattice matching constraints. A new concept for fabricating material systems using the atomically abrupt and low dimensional nature of layered materials, called van der Waals epitaxy (VDWE), has been developed. GaSe (Eg = 2.1 eV) has been deposited on the three dimensional surface of GaAs (111) using a molecular beam deposition system. GaSe was evaporated from a single Knudsen source, impinging on a heated substrate. Even with a lattice mismatch of 6% between the substrate and the growing film, good quality single crystal films were grown as determined by RHEED. The films have further been analyzed using a complementary combination of XPS and X-ray reflectivity.

scholarly journals Tuning adlayer-substrate interactions of graphene/h-BN heterostructures on Cu(111)–Ni and Ni(111)–Cu surface alloys

RSC Advances ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1916-1927
Author(s):  
Jianmei Huang ◽  
Qiang Wang ◽  
Pengfei Liu ◽  
Guang-hui Chen ◽  
Yanhui Yang
Keyword(s):  
Long Range ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Alloy Surface ◽  
Surface Alloys ◽  
Substrate Interactions

The evolution of the interface and interaction of h-BN and graphene/h-BN (Gr/h-BN) on Cu(111)–Ni and Ni(111)–Cu surface alloys versus the Ni/Cu atomic percentage on the alloy surface were comparatively studied by DFT-D2, including critical long-range van der Waals forces.

LONG RANGE FORCES BETWEEN HYDROGEN MOLECULES

1955 ◽  
Vol 33 (11) ◽  
pp. 668-678 ◽  
Author(s):  
F. R. Britton ◽  
D. T. W. Bean
Keyword(s):  
Wave Function ◽  
Long Range ◽  
Ground State ◽  
Close Agreement ◽  
Van Der Waals ◽  
Wave Functions ◽  
Numerical Factor ◽  
Hydrogen Molecules ◽  
Static Quadrupole

Long range forces between two hydrogen molecules are calculated by using methods developed by Massey and Buckingham. Several terms omitted by them and a corrected numerical factor greatly change results for the van der Waals energy but do not affect their results for the static quadrupole–quadrupole energy. By using seven approximate ground state H2 wave functions information is obtained regarding the dependence of the van der Waals energy on the choice of wave function. The value of this energy averaged over all orientations of the molecular axes is found to be approximately −11.0 R−6 atomic units, a result in close agreement with semiempirical values.

scholarly journals Coexistence of long-range orders in low-dimensional systems

2018 ◽  
Vol 91 (9) ◽  
Author(s):  
Sudhakar Yarlagadda ◽  
Peter B. Littlewood
Keyword(s):  
Long Range ◽  
Low Dimensional

The Difference of Serum Protein Transport between Echinosides and Verbascoside

2020 ◽  
Vol 42 (3) ◽  
pp. 369-369
Author(s):  
Ming Guo Ming Guo ◽  
Xiaoxue Zhao Xiaoxue Zhao ◽  
Peter E Brodelius Peter E Brodelius ◽  
Ling Fang Ling Fang ◽  
Zhihong Sun and Rui Wang Zhihong Sun and Rui Wang
Keyword(s):  
Molecular Modeling ◽  
Hydrogen Bonds ◽  
Serum Albumin ◽  
Protein Transport ◽  
Van Der Waals ◽  
Hydrolysis Product ◽  
Van Der Waals Forces ◽  
Molecular Structures ◽  
Hydrophobic Force ◽  
Binding Characteristics

Verbascoside (VER) is the enzymatic hydrolysis product of echinacoside (ECH). The molecular structures of ECH and VER have different glucosyl groups so they bind to serum albumin in different ways, resulting in different pharmacological actions. In this report, we have examined the binding characteristics between human serum albumin (HSA) and ECH/VER by molecular modeling and spectroscopic approaches. Molecular modeling revealed that VER bound to HSA mainly through hydrogen bonds, van der Waals forces and hydrophobic forces. The spectroscopic results showed that the interactions between HSA and VER/ECH involved a static binding process, and the bonding strength of the VER-HSA complex was stronger than that of the ECH-HSA complex. The value of the binding distances (r) was low, which indicated the occurrence of energy transfer. The reaction conformational pattern of HSA-VER and HSA-ECH gave a “two-state model” based on fluorescent phase diagram analysis. According to the thermodynamic model, the main forces between interaction of VER and HSA were hydrogen bonds and van der Waals forces, whereas the interaction between ECH and HSA was hydrophobic force. The fluorescence polarization analysis demonstrated that the interaction between HSA and VER or ECH generated a non-covalent complex. Compared with ECH, VER was more likely to bind with HSA because of its smaller molecular size and low polarity. The results of the spectral analysis concurred with the molecular modeling data, which provides a helpful reference for the study of the molecular reaction mechanism of VER/ECH binding to HSA.

Impact of domain disorder on optoelectronic properties of layered semimetal MoTe2

2D Materials ◽  
2021 ◽  
Author(s):  
Maanwinder P. Singh ◽  
Jonas Kiemle ◽  
Ilkay Ozdemir ◽  
Philipp Zimmermann ◽  
Takashi Taniguchi ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Topological Type ◽  
Optoelectronic Properties ◽  
Local Domain ◽  
Type Ii ◽  
Relaxation Dynamics ◽  
Weyl Semimetal ◽  
Ultrafast Relaxation ◽  
Low Dimensional ◽  
The Impact

Abstract We address the impact of crystal phase disorder on the generation of helicity-dependent photocurrents in layered MoTe2, which is one of the van der Waals materials to realize the topological type-II Weyl semimetal phase. Using scanning photocurrent microscopy, we spatially probe the phase transition and its hysteresis between the centrosymmetric, monoclinic 1T’ phase to the symmetry-broken, orthorhombic Td phase as a function of temperature. We find a highly disordered photocurrent response in the intermediate temperature regime. Moreover, we demonstrate that helicity-dependent and ultrafast photocurrents in MoTe2 arise most likely from a local breaking of the electronic symmetries. Our results highlight the prospects of local domain morphologies and ultrafast relaxation dynamics on the optoelectronic properties of low-dimensional van der Waals circuits.

Computer Simulation of Colloidal Aggregation Induced by Directionalism of Long Range van der Waals Forces

2007 ◽  
Vol 23 (08) ◽  
pp. 1241-1246 ◽  
Author(s):  
XIONG Hai-Ling ◽  
◽  
◽  
YUAN Yong-Zhi ◽  
LI Hang ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Long Range ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Colloidal Aggregation
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