ANALISIS KESTABILAN SISTEM DINAMIK PARTIKEL DALAM MEDAN POTENSIAL HARDCORE DOUBLE YUKAWA

Abstrak Paper ini mengkaji sistem dinamik partikel yang bergerak dalam pengaruh medan potensial Hardcore Double Yukawa (HCDY) [1]. Kajian ini difokuskan pada analisis kondisi stabil sistem dinamik dengan memanfaatkan sifat kestabilan linear. Massa partikel dalam sistem ini ditinjau sebagai fungsi koordinat, sehingga berbentuk lebih umum. Potensial HCDY digunakan dalam mengkonstruksi Hamiltonian sistem dan selanjutnya dipakai untuk menentukan matriks Jacobinya. Selanjutnya, nilai eigen matriks menjadi dasar menganalisis kestabilan sistem dinamik ini. Untuk sistem dengan potensial jenis ini, hanya dimungkinkan dua jenis kestabilan, yaitu saddle dan rotor. Syarat-syarat untuk kedua jenis kestabilan ini juga ditampilkan. Kata kunci: potensial Hard Core Double Yukawa; sistem dinamik; keadaan stabil Abstract This paper discusses the dynamical sistem of particle that move under the influence of the Hard Core Double Yukawa (HCDY) potential field[1]. This study focuses on analyzing the stable condition of the dynamical sistem by utilizing the nature of linear stability. The mass of particle in this system is depend on coordinate function, so its form is more general. The HCDY potential is used in constructing the Hamiltonian system and then used to determine the Jacobian matrix.Futhermore, the matrix eigenvalue is the basis for analyzing the stability of this dyanamical system. For systems with this type of potential, only two types of stability are possible, namely saddle and rotor. The conditions for both types of stability are also displayed. Keywords: Hard Core Double Yukawa potential; dynamical system; stability

THEORETICAL INVESTIGATIONS OF PROPERTIES OF HYDROGEN AND HELIUM MIXTURE BASED ON PERTURBATION THEORY

In this paper, we have investigated thermodynamic parameters of hydrogen and helium fluid mixture with assistance of statistical perturbation theory. The results have been compared with existing theoretical and Monte Carlo simulation methods based. Moreover, the effects of density, temperature and helium concentration on equation of state (EOS) of this mixture have been considered. Likewise, since exp-6 potential has given better results in comparison with MC simulations in higher temperatures than double Yukawa potential and avoiding any vague speculation, comparison between effects of these potentials has been presented. The results further suggest that EOS in this place depends sensitively on the density, the potential function and concentration of each component.

LIQUID–VAPOUR EQUILIBRIUM WITH DOUBLE YUKAWA POTENTIAL

A statistical mechanical based theory is developed for incorporating the long range correlations in the frame work of the first order perturbation theory to study the liquid–vapour equilibrium. The transition temperature and the liquid–vapour coexistence curves are found to depend considerably on the long range correlations and on the realistic radial distribution function. The calculated liquid–vapour equilibrium curves are in good agreement with the computer simulation results.

EFFECTIVE HARD-SPHERE DIAMETERS IN SIMPLE CLASSICAL FLUIDS AND APPLICATIONS TO DOUBLE YUKAWA POTENTIAL

We present an accurate method to determine the effective hard-sphere diameters for systems interacting via an arbitrary continuous potential within the Gibbs–Bogoliaubov variational approach. As a specific application we consider the double Yukawa (DY) model potential with potential parameters fitted such that they reproduce the Lennard–Jones potential. To assess the accuracy of the theory, we give a direct comparison of the thermodynamic properties with simulation results and with experimental data for Argon. Also, comparisons with previous models are made.