Welcome to Dr. Jim McNeill's Home Page at Macon State College
James H. McNeill, Ph.D., Assistant Professor of Chemistry, Division of Natural Sciences & Mathematics, Macon State College, 100 College Station Drive, Macon, Georgia 31206-5145, U.S.A.
Telephone: (478) 471-5673 Fax: (478) 471-2753 E-Mail: james.mcneill@maconstate.edu
Research Work in Molecular Dynamics Simulations
1. Modifications of the van der Waals Gas Equation to Match Experimental Data
Recently, the following modifications (Equations 2, 3, and 4 and an added a3-parameter) of the traditional van der Waals gas equation were utilized so that the van der Waals equation of state will match experimental data of xenon gas:
P = f R T / ( v − b ) − a2 / v 2 − a3 / v 3 Equation 1
b = ( b0 / 4 ) { 1 + [ 1 + 2 b02 ( 1 / v − 2 / b0 ) 2 ] 1/2 } Equation 2
b0 = c0 + c1 exp( − k1 / v ) Equation 3
f = 1 − ( c2 / v ) exp( − k2 / v2 ) Equation 4
This modified version matched experimental data of xenon within a range starting at the freezing point xenon (161.4 Kelvin) up to 1,000 Kelvin. Numerical values of parameters a2 and a3 were assumed to be constant and were evaluated using the experimentally observed second and third virial coefficient values, B and C, observed at different temperatures. The other additional parameters (c0, c1, c2, k1 , and k2) were evaluated using experimental data at the critical point and also below and above the measured critical temperature value of 289.7 Kelvin. These additional parameters were observed to change numerically with temperature, with discontinuity occurring in the curvatures at the critical temperature value of 289.7 Kelvin.
To learn more about this research work, click on the title below to obtain a recent copy of this work which has been typed out using Microsoft Word.
Modified van der Waals Gas Equation Derived from Experimental Data of Xenon
Also, the value of the c2-parameter was observed to approach zero rapidly for temperatures above the critical temperature value of 289.7 Kelvin. Molecular dynamics simulations using the hard-sphere model for 1,000 or more xenon gas atoms was used to develop the second equation above concerning the dependence of the van der Waals b-parameter upon the gas molar volume or molar density.
Hopefully in the near future, a paper for publication on this work will be submitted as well as the writing of a monograph.
2. Gaseous Diffusion in Microscopically Sized Zeolite Crystals using the Hard-Sphere Potential
In the near future, additional information will be added concerning this research endeavor. A large FORTRAN algorithm, PROGRAM MONSTER, has been developed to simulate the diffusion of a large number of gaseous atoms or molecules into a microscopically sized crystal of zeolite A or Y. Currently the algorithm is being modified in order that it can be successfully ran on a personal computer using Windows Office XP.
Recently, some results for the hypothetical diffusion of monatomic hydrogen in zeolites A have been obtained. To see these results, click on the title below to obtain a recent copy of this work typed out in Microsoft Word
Computer Simulation of Gas Diffusion within Zeolite Crystal
3. Classical Dynamic Simulations of Rigid Rotating Diatomic and Polyatomic Molecules
Also, in the near future, results from computer simulations of a large number of rigid-rotating diatomic and polyatomic molecular gases will be discussed at this web site. The hard-sphere potential is again employed along with classical physics. Modifications of presently developed software is necessary in order that these simulations can be performed using a personal computer. One of the first most important observed results from these simulations is that regarding diatomic gases. The rotational frequency distributions of simulated diatomic molecular gases deviate consistently from the Maxwellian distribution. This is due to asymmetry of a diatomic molecule. Yet, the velocity distributions continuously displayed the Maxwellian distribution in correlation with the classical kinetic theory of gases.
---------------------------------------------------------------------------------------------------------------------------------------------------------
Mr. Peabody's Improbable History of Science
Mr. Peabody: Now Sherman, if you be so kind, please set the Waybac Machine to the first decade of the 21st Century at the location of Macon State College in Macon, Georgia, USA. Professor Jim McNeill could surely use some help from Mr. Peabody when it comes to mathematically modeling Avogadro's Number of gaseous particles, that is 6.022 ´ 1023 gaseous particles, Sherman. Back then computers could only handle around 100,000 or less particles.
Sherman: Sure thing, Mr. Peabody! But Mr. Peabody, that was a long time ago before humans knew anything about being a Time-Travelor.
Mr. Peabody: Now Sherman, don't worry yourself too much about this matter, since Time-Traveling ONLY became possible when we BEAGLES evolved beyond you Humans! "RUFF!! RUFF!!"