We report, from direct observation of particle trajectories as a function time, the presence stringlike cooperative motion in quasi-two-dimensional liquid. have used digital video microscopy to study equilibrium dynamics suspensions sterically stabilized uncharged poly(methylmethacrylate) spheres confined thin glass cell. Our experiments reveal existence, semidilute and dense liquid states, transition qualitative dynamical behavior system. At short times particles undergo unhindered Brownian...

The evolution of a mixed quantum-classical system is expressed in the mapping formalism where discrete quantum states are mapped onto oscillator states, resulting phase space description degrees freedom. By defining projection operators corresponding to physical it shown that Liouville operator commutes with so dynamics confined space. It also trajectory-based solution this equation can be constructed requires simulation an ensemble entangled trajectories. An approximation which retains only...

In this paper the ab initio potential of mean force for formic acid–water system is calculated in a Monte Carlo simulation using classical fluctuating charge molecular mechanics to guide updates. The energies are density-functional theory (DFT) methods recently developed by Salahub et al. [J. Chem. Phys. 107, 6770 (1997)] describe hydrogen-bonded systems. Importance sampling used investigate structural changes and it demonstrated that importance function can improve efficiency DFT several...

Collective motion in nonequilibrium steady state suspensions of self-propelled Janus motors driven by chemical reactions can arise due to interactions coming from direct intermolecular forces, hydrodynamic flow effects, or chemotactic effects mediated gradients. The relative importance these depends on the reactive characteristics motors, way which system is maintained a state, and properties suspension, such as volume fraction. From simulations microscopic hard collision model for...

The dynamics of a quantum system coupled to classical environment and subject constraints that drive it out equilibrium are described. evolution the is governed by quantum–classical Liouville equation. Rather than evaluating mixed density operator, we derive exact equations motion for nonequilibrium average values set operators or variables, along with correlation function expressions dissipative coefficients enter these equations. These obtained requiring averages equal local depend on...

The mixed quantum-classical Liouville equation is derived from a semiclassical perspective starting the full quantum Schrödinger equation. An asymptotic numerical scheme for solving discussed which relies on propagating swarms of interacting “threads” represent density matrix or other observable. It demonstrated that this “multithreads” method performs extremely well simple one-dimensional model systems designed to test nonadiabatic molecular dynamic methods, yielding essentially exact...

Elegant integration schemes of second and fourth order for simulations rigid-body systems are presented which treat translational rotational motion on the same footing. This is made possible by a recent implementation exact solution free motion. The two time reversible symplectic, exactly respect conservation principles both total linear angular momentum vectors. Simulations simple test show that second-order scheme stable conserves all constants to high precision. Furthermore, demonstrated...

A microscopic model for Janus motors captures essential features of the diffusiophoretic mechanism and will facilitate large-scale simulations designed to probe collective behavior many motors.

Abstract Molecular dynamics simulations were conducted for a cubic Cu cluster supported on graphite bilayer. The Sutten–Chen and Lennard–Jones potentials used metal–metal metal–graphite interactions, respectively. Heating cooling processes performed by NVT at different temperatures in the range 200 to 1800 K. melting point was identified basis of caloric heat capacity curves. calculated 770 K, far below bulk crystalline copper. Several phenomena such as appearance hysteresis...

Double-layer graphyne sheets with carefully chosen layer spacing are promising candidates as membranes in reverse osmosis desalination.

In this article, an exact surface-hopping procedure and approximate asymptotic method for performing molecular dynamics based on a mixed quantum-classical Liouville equation [J. Chem. Phys. 110, 8919 (1999)] partially Wigner transformed dynamical variables of coupled quantum subsystem classical bath are elaborated. The methods upon writing the equations motion in basis set which transitions do not alter trajectory, therefore avoid ad-hoc momentum jump approximations free singular kernels...

The multithreads algorithm for solving the mixed quantum-classical Liouville equation is extended to systems in which multiple classical degrees of freedom couple explicitly a quantum subsystem. method involves evolving discrete set matrices representing operators positioned at phase space coordinates according precise dynamical rules dictated by evolution equations. propagation scheme based on Trotter expansion time operator and trajectory (thread) branching pruning operations each step....

A general framework for performing event-driven simulations of systems with semi-flexible or rigid bodies interacting under impulsive torques and forces is outlined. Two different approaches are presented. In the first, dynamics interaction rules derived from Lagrangian mechanics in presence constraints. This approach most suitable when body composed relatively few point masses semi-flexible. second method, equations used to derive explicit analytical expressions free evolution arbitrary...

Active media, whose constituents are able to move autonomously, display novel features that differ from those of equilibrium systems. In addition naturally-occurring active systems such as populations swimming bacteria, synthetic self-propelled nanomotors have been developed. These interesting because their potential applications in a variety fields. Janus particles, motors spherical geometry with one hemisphere catalyzes the conversion fuel product and noncatalytic hemisphere, can propel...

The single-particle and collective dynamics of systems comprising Janus motors, solvent, reactive solute species maintained in nonequilibrium states are investigated. Reversible catalytic reactions with the take place on faces established either by imposing constant-concentration reservoirs that feed remove or through out-of-equilibrium fluid phase reactions. We consider general intermolecular interactions between motor hemispheres species. For single we show reaction rate depends...

We present a derivation from the first principles of coupled equations motion an active self-diffusiophoretic Janus motor and hydrodynamic densities its fluid environment that are nonlinearly displaced equilibrium. The makes use time-dependent projection operator techniques defined in terms slowly varying coarse-grained microscopic species number, total momentum, energy. exact simplified using time scale arguments, resulting Markovian for linear angular velocities with average forces torques...

In this paper various extensions of the parallel-tempering algorithm are developed and their properties analyzed. The algorithms designed to alleviate quasiergodic sampling in systems which have rough energy landscapes by coupling individual Monte Carlo chains form a composite chain. As with parallel tempering, procedures based upon extending state space include parameters encourage mobility. One drawbacks method is stochastic nature dynamics auxiliary variables extend space. work,...

Defects, which naturally occur in nanostructures such as nanotubes, have a profound effect on their structure and electronic properties, it is important to include them the computational studies involving these nanotubes. In this Article, density functional theory calculations are utilized investigate impact of topological Stone-Wales (SW) vacancy defects structural properties zigzag BC3 nanotube. It demonstrated that most stable state for SW defect an axial C–C bond rotated by 90°. For...