Evaluation of the selectivity of the epoxidation of cis- versus trans-alkenes by oxo[meso-tetrakis(2,6-dibromophenyl)porphinato]chromium(V). Dynamics, products, and Van der Waals energies

1991 ◽  
Vol 113 (15) ◽  
pp. 5644-5650 ◽  
Author(s):  
Gong Xin He ◽  
Houng Yau Mei ◽  
Thomas C. Bruice
Keyword(s):  
Van Der Waals ◽  
Van Der Waals Energies

scholarly journals Complexity and Convergence of Electrostatic and van der Waals Energies within PME and Cutoff Methods

2004 ◽  
Vol 5 (4) ◽  
pp. 154-173 ◽  
Author(s):  
Radka Vařeková ◽  
Jaroslav Koča ◽  
Chang-Guo Zhang
Keyword(s):  
Van Der Waals ◽  
Van Der Waals Energies

scholarly journals van der Waals Energies in Density Functional Theory

1998 ◽  
Vol 80 (19) ◽  
pp. 4153-4156 ◽  
Author(s):  
Walter Kohn ◽  
Yigal Meir ◽  
Dmitrii E. Makarov
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Van Der Waals ◽  
Functional Theory ◽  
Van Der Waals Energies

scholarly journals Macroscale adhesion of gecko setae reflects nanoscale differences in subsurface composition

2013 ◽  
Vol 10 (78) ◽  
pp. 20120587 ◽  
Author(s):  
Peter Loskill ◽  
Jonathan Puthoff ◽  
Matt Wilkinson ◽  
Klaus Mecke ◽  
Karin Jacobs ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Interfacial Adhesion ◽  
Theoretical Calculations ◽  
Van Der Waals ◽  
Adhesion Forces ◽  
Inhomogeneous Materials ◽  
Subsurface Layers ◽  
Adhesion Mechanics ◽  
Van Der Waals Energies ◽  
Theoretical Results

Surface energies are commonly used to determine the adhesion forces between materials. However, the component of surface energy derived from long-range forces, such as van der Waals forces, depends on the material's structure below the outermost atomic layers. Previous theoretical results and indirect experimental evidence suggest that the van der Waals energies of subsurface layers will influence interfacial adhesion forces. We discovered that nanometre-scale differences in the oxide layer thickness of silicon wafers result in significant macroscale differences in the adhesion of isolated gecko setal arrays. Si/SiO 2 bilayer materials exhibited stronger adhesion when the SiO 2 layer is thin (approx. 2 nm). To further explore how layered materials influence adhesion, we functionalized similar substrates with an octadecyltrichlorosilane monolayer and again identified a significant influence of the SiO 2 layer thickness on adhesion. Our theoretical calculations describe how variation in the SiO 2 layer thickness produces differences in the van der Waals interaction potential, and these differences are reflected in the adhesion mechanics. Setal arrays used as tribological probes provide the first empirical evidence that the ‘subsurface energy’ of inhomogeneous materials influences the macroscopic surface forces.

Computing van der Waals energies in the context of the rotamer approximation

2007 ◽  
Vol 68 (4) ◽  
pp. 863-878 ◽  
Author(s):  
Gevorg Grigoryan ◽  
Alejandro Ochoa ◽  
Amy E. Keating
Keyword(s):  
Van Der Waals ◽  
Van Der Waals Energies

Experimental Determination of van der Waals Energies in a Biological System

2007 ◽  
Vol 46 (34) ◽  
pp. 6453-6456 ◽  
Author(s):  
Martin A. Wear ◽  
Daphne Kan ◽  
Amir Rabu ◽  
Malcolm D. Walkinshaw
Keyword(s):  
Experimental Determination ◽  
Biological System ◽  
Van Der Waals ◽  
Van Der Waals Energies

scholarly journals A Novel Constraint for the Simplified Description of Dispersion Forces

2000 ◽  
Vol 53 (4) ◽  
pp. 575 ◽  
Author(s):  
John F. Dobson ◽  
Bradley P. Dinte ◽  
Jun Wang ◽  
Tim Gould
Keyword(s):  
Van Der Waals ◽  
Local Version ◽  
Dispersion Forces ◽  
Response Functions ◽  
Electron Systems ◽  
Planar Systems ◽  
Semi Empirical ◽  
Exact Constraint ◽  
Direct Use ◽  
Van Der Waals Energies

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.

scholarly journals O(N)Stochastic Evaluation of Many-Body van der Waals Energies in Large Complex Systems

2021 ◽  
Author(s):  
Pier Paolo Poier ◽  
Louis Lagardère ◽  
Jean-Philip Piquemal
Keyword(s):  
Density Functional ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Complex Materials ◽  
Many Body ◽  
Functional Theory ◽  
Molecular Systems ◽  
New Strategy ◽  
The Many ◽  
Van Der Waals Energies

We propose a new strategy to solve the Tkatchenko-Scheffler Many-Body Dispersion (MBD) model’s equations. Our approach overcomes the original O(N**3) computational complexity that limits its applicability to large molecular systems within thecontext of O(N) Density Functional Theory (DFT). First, in order to generate the required frequency-dependent screenedpolarizabilities, we introduce an efficient solution to the Dyson-like self-consistent screening equations. The scheme reducesthe number of variables and, coupled to a DIIS extrapolation, exhibits linear-scaling performances. Second, we apply astochastic Lanczos trace estimator resolution to the equations evaluating the many-body interaction energy of coupled quantumharmonic oscillators. While scaling linearly, it also enables communication-free pleasingly-parallel implementations. As the resulting O(N) stochastic massively parallel MBD approach is found to exhibit minimal memory requirements, it opens up the possibility of computing accurate many-body van der Waals interactions of millions-atoms’ complex materials and solvated biosystems with computational times in the range of minutes.

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