Improved First-Principles Calculation of the Third Virial Coefficient of Helium
نویسندگان
چکیده
We employ state-of-the-art pair and three-body potentials with path-integral Monte Carlo (PIMC) methods to calculate the third density virial coefficient C(T) for helium. The uncertainties are much smaller than those of the best experimental results, and approximately one-fourth the uncertainty of our previous work. We have extended our results in temperature down to 2.6 K, incorporating the effect of spin statistics that become important below approximately 7 K. Results are given for both the (3)He and (4)He isotopes. We have also performed PIMC calculations of the third acoustic virial coefficient γ a; our calculated values compare well with the limited experimental data available. A correlating equation for C(T) of (4)He is presented; differentiation of this equation provides a reliable and simpler way of calculating γ a.
منابع مشابه
First-Principles Calculation of the Third Virial Coefficient of Helium
Knowledge of the pair and three-body potential-energy surfaces of helium is now sufficient to allow calculation of the third density virial coefficient, C(T), with significantly smaller uncertainty than that of existing experimental data. In this work, we employ the best available pair and three-body potentials for helium and calculate C(T) with path-integral Monte Carlo (PIMC) calculations sup...
متن کاملAb initio interaction potential of methane and carbon dioxide: Calculation of second-virial coefficient
An interaction potential at different orientation for the CH4 and CO2 complex was derived at theB3LYP level of theory and 6-31+G* basis sets. The potential energy surface was computed on somemolecular geometries. The complete basis set limit of the interaction energies were fitted to wellknownanalytical functions. To determine the second virial coefficients B, U(r) is used to obtain themodel’s ...
متن کاملAn Improved Correlation for Second Virial Coefficients of Pure Fluids
In the present work, a modified correlation is presented for the second virial coefficients of both polar and nonpolar fluids based on the corresponding states principle. The second virial coefficients of gaseous polar and non-polar compounds were calculated and compared with experimental data and with other correlations. Comparisons with the existing correlations show that the present work is ...
متن کاملSemiclassical fifth virial coefficients for improved ab initio helium -‐ 4 standards
For helium-4, we present ab initio, semiclassical calculations of virial coefficients B n for n = 2, 3, 4, and 5 from 50 K to 1000 K. Using our values of B 4 and B 5 and the more accurate literature values of B 2 and B 3 , we argue that the ab initio virial equation of state is more accurate than recent, high-quality, densimeter measurements spanning the range {223 K < T < 500 K, p < 38 MPa}. T...
متن کاملA. Collision-Induced Light Scattering in Helium Gas B. Second Dielectric Virial Coefficient of Helium Gas C. Rovibrational Spectra of Weakly Bound Complexes: He-CO and He-HF D. Excess Second Virial Coefficients for He-CO
The present status of symmetry-adapted perturbation theory applied to intermolecular potentials and interaction-induced properties is presented, and illustrated by means of applications to the calculations of the collisioninduced Raman spectra, rovibrational spectra of weakly bound dimers, and second (pressure and dielectric) virial coefficients.
متن کامل