相关论文: Pressure and density of vacancies in solid $^4$He
We are investigating the properties of vacancies in solid 4He with the exact zero temperature SPIGS method. Our aim is to study the possibility of phase--separation between vacancies and the perfect crystal. We find a significant…
The changes that vacancies produce in the properties of hcp solid 4He are studied by means of quantum Monte Carlo methods. Our results show that the introduction of vacancies produces significant changes in the behavior of solid 4He, even…
We studied the thermal effects on the behavior of incommensurate solid $^4$He at low temperatures using the path integral Monte Carlo method. Below a certain temperature, depending on the density and the structure of the crystal, the…
It is pointed out that simulation computation of energy performed so far cannot be used to decide if the ground state of solid 4He has the number of lattice sites equal to the number of atoms (commensurate state) or if it is different…
We investigate the phase transition of Bose-Einstein particles with the hard-core repulsion in the grand canonical ensemble within the Van der Waals approximation. It is shown that the pressure of non-relativistic Bose-Einstein particles is…
We study theoretically and numerically the elastic properties of hard sphere glasses, and provide a real-space description of their mechanical stability. In contrast to repulsive particles at zero-temperature, we argue that the presence of…
Defects are believed to play a fundamental role in the supersolid state of 4He. We have studied solid 4He in two dimensions (2D) as function of the number of vacancies n_v, up to 30, inserted in the initial configuration at rho = 0.0765…
Indistinguishability of particles is a major factor destabilizing crystalline order in Bose systems. We describe this effect in terms of damped quasi-particle modes and in the dual language of Feynman paths, and illustrate it by…
We examine the effect of vacancies on the phase behavior and structure of systems consisting of hard cubes using event-driven molecular dynamics and Monte Carlo simulations. We find a first-order phase transition between a fluid and a…
Vortex states in the mixture of ultracold atomic clouds of bosons and fermions are investigated using the effective Hamiltonian for the Bose subsystem. A stability of the Bose system in the case of attractive interaction between components…
Defects are believed to play a fundamental role in the supersolid state of 4He. We report on studies by exact Quantum Monte Carlo (QMC) simulations at zero temperature of the properties of solid 4He in presence of many vacancies, up to 30…
Although both vacancies and interstitial have relatively high activation energies in the normal solid, we propose that a lower energy bound state of a vacancy and an interstitial may facilitate vacancy condensation to give supersolidity in…
Equation of state of He-4 hcp crystals with vacancies is determined at zero temperature using the diffusion Monte Carlo technique, an exact ground state zero-temperature method. This allows us to extract the formation enthalpy and isobaric…
We study the connections among particle statistics, frustration, and ground-state energy in quantum many-particle systems. In the absence of interaction, the influence of particle statistics on the ground-state energy is trivial: the…
We study the phase diagram of a two-dimensional assembly of bosons interacting via a soft core repulsive pair potential of varying strength, and compare it to that of the equivalent system in which particles are regarded as distinguishable.…
We study in random-phase approximation the newly discovered supersolid phase of ${}^4$He and present in detail its finite temperature properties. ${}^4$He is described within a hard-core quantum lattice gas model, with nearest and…
Displacements of atoms and molecules away from lattice sites in helium and parahydrogen solids at low temperature have been studied by means of Quantum Monte Carlo simulations. In the bcc phases of He-3 and He-4, atomic displacements are…
Recent theoretical and experimental work on solid He-4 has focused on vacancies, or other lattice defects and whether these can form a Bose-Einstein condensate within the solid. The earliest suggestion that this could happen was based on…
Fluctuations of the number of condensed atoms in a finite-size, weakly interacting Bose gas confined in a box potential are investigated for temperatures up to the critical region. The canonical partition functions are evaluated using a…
The ground state of solid $^4$He is studied using the diffusion Monte Carlo method and a new trial wave function able to describe the supersolid. The new wave function is symmetric under the exchange of particles and reproduces the…