170 research outputs found
Thermodynamic Properties of Correlated Strongly Degenerate Plasmas
An efficient numerical approach to equilibrium properties of strongly coupled
systems which include a subsystem of fermionic quantum particles and a
subsystem of classical particles is presented. It uses an improved path
integral representation of the many-particle density operator and allows to
describe situations of strong coupling and strong degeneracy, where analytical
theories fail. A novel numerical method is developed, which allows to treat
degenerate systems with full account of the spin scatistics. Numerical results
for thermodynamic properties such as internal energy, pressure and pair
correlation functions are presented over a wide range of degeneracy parameter.Comment: 8 pages, 4 figures, uses sprocl.sty (included) to be published in
"Progress in Nonequilibrium Green's functions", M. Bonitz (Ed.), World
Scientific 200
Strict derivation of angular-averaged Ewald potential
In this work we strictly derive an angular-averaged Ewald potential suitable
for numerical simulations of disordered Coulomb systems. The potential was
first introduced by E. Yakub and C. Ronchi without strict mathematical
justification. Two methods are used to find the coefficients of the series
expansion of the potential: based on the Euler-Maclaurin and Poisson summation
formulas. The expressions for each coefficient is represented as a finite
series containing derivatives of Jacobi theta functions. We also demonstrate
the formal equivalence of the Poisson and Euler-Maclaurin summation formulas in
the three-dimensional case. The effectiveness of the angular-averaged Ewald
potential is shown by the example of calculating the Madelung constant for a
number of crystal lattices
Pressure of Coulomb systems with volume-dependent long-range potentials
In this work, we consider the pressure of Coulomb systems, in which particles
interact via a volume-dependent potential (in particular, the Ewald potential).
We confirm that the expression for virial pressure should be corrected in this
case. We show that the corrected virial pressure coincides with the formula
obtained by differentiation of free energy if the potential energy is a
homogeneous function of particle coordinates and a cell length. As a
consequence, we find out that the expression for pressure in the recent paper
by J. Liang \textit{et al.} [\href{https://doi.org/10.1063/5.0107140}{J. Chem.
Phys. \textbf{157}, 144102 (2022)}] is incorrect
Exchange--correlation bound states of the triplet soft--sphere fermions by the path integral Monte Carlo simulations
Path integral Monte Carlo simulations in the Wigner approach to quantum
mechanics has been applied to calculate momentum and spin--resolved radial
distribution functions of the strongly correlated soft--sphere quantum
fermions. The obtained spin--resolved radial distribution functions demonstrate
arising triplet clusters of fermions, that is the consequence of the
interference of exchange and interparticle interactions. The semiclassical
analysis in the framework of the Bohr--Sommerfeld quantization condition
applied to the potential of the mean force corresponding to the same--spin
radial distribution functions allows to detect exchange--correlation bound
states in triplet clusters and to estimate corresponding averaged energy
levels. The obtained momentum distribution functions demonstrate the narrow
sharp separated peaks corresponding to bound states and disturbing the
Maxwellian distribution.Comment: arXiv admin note: substantial text overlap with arXiv:2305.0760
Thermodynamic properties and electrical conductivity of strongly correlated plasma media
We study thermodynamic properties and the electrical conductivity of dense
hydrogen and deuterium using three methods: classical reactive Monte Carlo
(REMC), direct path integral Monte Carlo (PIMC) and a quantum dynamics method
in the Wigner representation of quantum mechanics. We report the calculation of
the deuterium compression quasi-isentrope in good agreement with experiments.
We also solve the Wigner-Liouville equation of dense degenerate hydrogen
calculating the initial equilibrium state by the PIMC method. The obtained
particle trajectories determine the momentum-momentum correlation functions and
the electrical conductivity and are compared with available theories and
simulations
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