arXiv subjects

Tsogbayar Tsednee

Publications and source records attributed to Tsogbayar Tsednee.

7 recordsLinked to original sources

arXiv2024

Equilibrium thermodynamic properties of binary hard-sphere mixtures from integral equation theory

The binary additive hard-sphere mixtures have been studied by the Ornstein-Zernike integral equation coupled with the Martynov-Sarkisov (MS) closure approximation. Virial equation of state is computed in the MS approximation. The excess chemical potential for the mixture is evaluated with a closed-form expression based on correlation functions. The excess Helmholtz free energy is obtained using the Euler relation of thermodynamics. Moreover, these thermodynamic quantities are obtained by the Boublík-Mansoori-Carnahan-Starling-Leland (BMCSL) formulas. Our findings for pressure and excess chemical potential for a number of binary sets of the mixtures from the MS approximation show good agreements with those obtained by the BMCSL formulas and available data in literature, having a maximum deviation of $5\%$ for a packing fraction up to 0.5. The maximum deviation of the excess free energy obtained for the mixtures is shown to be $\sim 16\%$ for a packing fraction of 0.5. To our knowledge, this work presents an initial calculation of an excess chemical potential of the system in the MS approximation.

cond-mat.stat-mech↗

arXiv2023

Pressure consistency for binary hard-sphere mixtures from an integral equation approach

The site-site Ornstein-Zernike equation combined with the Verlet-modified bridge function has been applied to the binary hard sphere mixtures and pressure consistency has been tested. An equation of state has been computed for the case where a packing fraction is $η= 0.49$, diameter ratios are $σ_{2}/σ_{1} = 0.3$ and $0.6$, and the mole fractions are $x_{1} = 0.125, 0.5, 0.75$, and $1$. An excess chemical potential for each component has been obtained as well. Our findings for thermodynamic properties are in good agreement with available data in literature.

cond-mat.stat-mech↗

arXiv2023

Calculation of the entropy for hard-sphere from integral equation method

The Ornstein-Zernike integral equation method has been employed for a single-component hard sphere fluid in terms of the Percus-Yevick (PY) and Martynov-Sarkisov (MS) approximations. Virial equation of state has been computed in both approximations. An excess chemical potential has been calculated with an analytical expression based on correlation functions, and the entropy has been computed with a thermodynamic relation. Calculations have been carried out for a reduced densities of 0.1 to 0.9. It has been shown that the MS approximation gives better values than those from the PY approximation, especially for high densities and presents a reasonable comparison with available data in the literature.

cond-mat.stat-mech↗

arXiv2023

Numerical solution to the time-dependent Gross-Pitaevskii equation

In this work we employ the split-step technique combined with a Legendre pseudospectral representation to solve various time-dependent Gross-Pitaevskii equations (GPE). Our findings based on the numerical accuracy of this approach applied for one-dimensional (1D) and two-dimensional (2D) problems show that it can provide accurate and stable solutions. Moreover, this approach has been applied to study the dynamics of the Bose-Einstein condensate which is modeled with the GPE. The breathing of condensate with an repulsive and attractive interactions trapped in 1D and 2D harmonic potentials has been simulated as well.

physics.atom-ph↗

arXiv2022

Numerical solution to the time-independent Gross-Pitaevskii equation

We solve the time-independent Gross-Pitaevskii equation modeling the Bose-Einstein condensate trapped in an anistropic harmonic potential using a pseudospectral method. Numerically obtained values for an energy and a chemical potential for the condensate with positive and negative scattering length have been compared with those from the literature. The results show that they are in good agreement when an atomic interaction is not too strong.

physics.atom-ph↗

arXiv2022

An excess chemical potential for binary hard-sphere mixtures from integral equation theory

We solve the site-site Ornstein-Zernike equation using the Percus-Yevick closure for binary hard-sphere mixture. We calculate an excess chemical potential for the mixture's diameter ratios of 0.3, 0.5, 0.6 and 0.9, and at packing fraction of 0.49 using the analytical expression. Our numerical results are in good agreement with those in the literature.

cond-mat.stat-mech↗

arXiv2015

A method for accurate electron-atom resonances: The complex-scaled multiconfigurational spin-tensor electron propagator method for the $^2P\, \mbox{Be}^{-}$ shape resonance problem

We propose and develop the complex scaled multiconfigurational spin-tensor electron propagator (CMCSTEP) technique for theoretical determination of resonance parameters with electron-atom/molecule systems including open-shell and highly correlated atoms and molecules. The multiconfigurational spin-tensor electron propagator method (MCSTEP) developed and implemented by Yeager his coworkers in real space gives very accurate and reliable ionization potentials and attachment energies. The CMCSTEP method uses a complex scaled multiconfigurational self-consistent field (CMCSCF) state as an initial state along with a dilated Hamiltonian where all of the electronic coordinates are scaled by a complex factor. CMCSCF was developed and applied successfully to resonance problems earlier. We apply the CMCSTEP method to get $^2 P\,\mbox{Be}^{-}$ shape resonance parameters using $14s11p5d$, $14s14p2d$, and $14s14p5d$ basis sets with a $2s2p3d$\,CAS. The obtained value of the resonance parameters are compared to previous results. This is the first time CMCSTEP has been developed and used for a resonance problem. It will be among the most accurate and reliable techniques. Vertical ionization potentials and attachment energies in real space are typically within $\pm 0.2\,eV$ or better of excellent experiments and full configuration interaction calculations with a good basis set. We expect the same sort of agreement in complex space.

physics.atom-ph↗