Dispersion forces between weakly disordered van der Waals crystals

We propose a novel use of an exact constraint in the construction of simple approximations for response functions of interacting many-electron systems. Within its simplest local version, the resulting theory gives improved approximations for static atomic dipolar polarisabilities without the direct use of wavefunctions or semi-empirical cutoffs. It leads to correct van der Waals energies between distant planar systems, but over-corrects existing cutoff theories for the van der Waals C 6 coefficient for atoms. It is argued that a nonlocal-response version of the constrained theory will do better.

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The measurement of van der Waals dispersion forces in the range 1.5 to 130 nm

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1972.0162 ◽

1972 ◽

Vol 331 (1584) ◽

pp. 19-38 ◽

Cited By ~ 526

Keyword(s):

Experimental Study ◽

Fatty Acid ◽

Dynamic Method ◽

Van Der Waals ◽

The Other ◽

Gradual Transition ◽

Dispersion Forces ◽

Spring Stiffness ◽

20 Nm ◽

Stiff Spring

.This paper describes an experimental study of the van der Waals dispersion forces between curved mica surfaces. For separations in the range 1.4 to 20 nm the forces were determined by the jump method described in earlier work by Tabor & Winterton (1969). For larger separations the forces were determined by a new dynamic method. One surface was supported on a rigid piezo-electric crystal and could be set vibrating at very small amplitudes over a convenient range of frequencies. The other was supported, facing it, on a stiff spring: its natural frequency depended both on the spring stiffness and on the van der Waals force exerted upon its by the first surface. By determining the resonant frequency as a function of separation the law of force was deduced in the range 10 to 130 nm. Both methods thus covered the range from 1.4 to 130 nm. In this way it is shown that there is a gradual transition between non-retarded and retarded forces as the separation is increased from 12 to 50nm. Experiments have also been carried out on the influence of adsorbed fatty acid monolayers on the van der Waals interaction between mica surfaces. The results show that for separations greater than about 5 nm the forces are as for bulk mica: for separations less than 3 nm the forces are slightly less and appear to be dominated by the van der Waals properties of the monolayers themselves.

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Van der Waals and Capillary Adhesion of Microelectromechanical Systems

Microelectromechanical Systems ◽

10.1115/imece2006-15169 ◽

2006 ◽

Cited By ~ 1

Author(s):

Frank W. DelRio ◽

Maarten P. de Boer ◽

Leslie M. Phinney ◽

Chris J. Bourdon ◽

Martin L. Dunn

Keyword(s):

Microelectromechanical Systems ◽

Capillary Condensation ◽

Van Der Waals ◽

Dispersion Forces ◽

Surface Adhesion ◽

Surface Separation ◽

Capillary Adhesion ◽

Close Proximity ◽

Large Roughness ◽

Deposition Technology

Interfacial adhesion is an important factor in determining the performance and reliability of microelectromechanical systems (MEMS). Van der Waals dispersion forces are the dominant adhesion mechanism in the low relative humidity (RH) regime. At small roughness values, adhesion is mainly due to van der Waals dispersion forces acting across extensive non-contacting areas and is related to 1/Dave2, where Dave is the average surface separation. These contributions must be considered due to the close proximity of the surfaces, which is a result of the planar deposition technology. At large roughness values, van der Waals forces at contacting asperities become the dominating contributor to the adhesion. Capillary condensation of water has a significant effect on rough surface adhesion in the moderate to high RH regime. Above a threshold RH, which is a function of the surface roughness, the adhesion jumps due to meniscus formation at the interface and increases rapidly towards the upper limit of Γ=2 γcos θ=144 mJ/m2, where γ is the liquid surface energy and θ is the contact angle.

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Van der Waals Dispersion Forces between Dielectric Nanoclusters

Langmuir ◽

10.1021/la061802w ◽

2007 ◽

Vol 23 (4) ◽

pp. 1735-1740 ◽

Cited By ~ 60

Author(s):

Hye-Young Kim ◽

Jorge O. Sofo ◽

Darrell Velegol ◽

Milton W. Cole ◽

Amand A. Lucas

Keyword(s):

Van Der Waals ◽

Dispersion Forces

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Van der Waals and Casimir–Polder dispersion forces

Forces of the Quantum Vacuum ◽

10.1142/9789814644761_0003 ◽

2015 ◽

pp. 61-106 ◽

Cited By ~ 1

Author(s):

EPHRAIM SHAHMOON

Keyword(s):

Van Der Waals ◽

Dispersion Forces

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Effects of capillary and van der Waals dispersion forces on the equilibrium profile of a wetting liquid: Theory and experiment

The Journal of Chemical Physics ◽

10.1063/1.452922 ◽

1987 ◽

Vol 87 (7) ◽

pp. 4180-4188 ◽

Cited By ~ 87

Author(s):

Jack G. Truong ◽

Peter C. Wayner

Keyword(s):

Van Der Waals ◽

Dispersion Forces ◽

Liquid Theory ◽

Equilibrium Profile ◽

Theory And Experiment ◽

Wetting Liquid

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van der Waals dispersion forces in electromagnetic fields

Physical Review A ◽

10.1103/physreva.53.3484 ◽

1996 ◽

Vol 53 (5) ◽

pp. 3484-3489 ◽

Cited By ~ 36

Author(s):

Peter W. Milonni ◽

Adolph Smith

Keyword(s):

Electromagnetic Fields ◽

Van Der Waals ◽

Dispersion Forces

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Theoretical Study of H2...I- van der Waals Anion Complex

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20050797 ◽

2005 ◽

Vol 70 (6) ◽

pp. 797-810 ◽

Cited By ~ 1

Author(s):

Michal Ilčin ◽

Vladimír Lukeš ◽

Viliam Laurinc ◽

Stanislav Biskupič

Keyword(s):

Interaction Energy ◽

Energy Surface ◽

Theoretical Study ◽

Van Der Waals ◽

Dispersion Forces ◽

Physical Origin ◽

Anion Complex ◽

Linear Configuration ◽

Well Depth ◽

Hf Wave

The ab initio potential energy surface (PES) for the weak interaction of hydrogen molecule with iodine anion is presented. The surface was obtained by the supermolecular method at the MP4(SDTQ) level of theory. Our calculations indicate the van der Waals (vdW) system for the linear configuration at rH-H = 0.752 Å and R = 3.76 Å with a well depth of De = 2096 μEh. The presented PES reveals also a transition state for the perpendicular arrangement at rH-H = 0.7416 Å and R = 4.63 Å with an interaction energy of -113 μEh. The physical origin of stability of the vdW H2...I- structure with respect to the H2...X- (X = F, Cl, Br) one was analysed by the symmetry adapted perturbation theory (SAPT) based on the single determinant HF wave function. The separation of the interaction energy shows that the dispersion forces play a much more important role for the systems with Cl, Br and I than for H2...F- and their importance slightly increases in the order Cl < Br < I. The global importance of the electrostatic and the induction energies decreases in the order F > Cl > Br > I.

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