Ab initio Calculation of Fluid Properties for Precision Metrology

Abstract

Recent advances regarding the interplay between ab initio calculations and metrology are reviewed, with particular emphasis on gas-based techniques used for temperature and pressure measurements. Since roughly 2010, several thermophysical quantities - in particular, virial and transport coefficients - can be computed from first principles without uncontrolled approximations and with rigorously propagated uncertainties. In the case of helium, computational results have accuracies that exceed the best experimental data by at least one order of magnitude and are suitable to be used in primary metrology. The availability of ab initio virial and transport coefficients contributed to the recent SI definition of temperature by facilitating measurements of the Boltzmann constant with unprecedented accuracy. Presently, they enable the development of primary standards of temperature in the range 2.5-552 K and pressure up to 7 MPa using acoustic gas thermometry, dielectric constant gas thermometry, and refractive index gas thermometry. These approaches will be reviewed, highlighting the effect of first-principles data on their accuracy. The recent advances in electronic structure calculations that enabled highly accurate solutions for the many-body interaction potentials and polarizabilities of atoms - particularly helium - will be described, together with the subsequent computational methods, most often based on quantum statistical mechanics and its path-integral formulation, that provide thermophysical properties and their uncertainties. Similar approaches for molecular systems, and their applications, are briefly discussed. Current limitations and expected future lines of research are assessed.

59 pages, 9 figures

References in corpus (17)

• ${\alpha }^4$ Ry corrections to singlet states of helium
• Pair potential with submillikelvin uncertainties and nonadiabatic treatment of the halo state of helium dimer
• QED calculation of the dipole polarizability of helium atom
• Sub-promille measurements and calculations of CO (3--0) overtone line intensities
• Development of a new UHV/XHV pressure standard (cold atom vacuum standard)
• Frequency-dependent polarizability of helium including relativistic effects with nuclear recoil terms
• Boltzmann bias grand canonical Monte Carlo
• Path-integral calculation of the fourth virial coefficient of helium isotopes
• Path-integral Monte Carlo worm algorithm for Bose systems with periodic boundary conditions
• First-principles calculation of the frequency-dependent dipole polarizability of argon
• Gas equilibration gas modulation refractometry (GEq-GAMOR) for assessment of pressure with sub-ppm precision
• Path-integral calculation of the third dielectric virial coefficient of noble gases
• Cross-calibration of atomic pressure sensors and deviation from quantum diffractive collision universality for light particles
• Equation of state of solid parahydrogen using ab initio two-body and three-body interaction potentials
• Collision-induced three-body polarizability of helium
• Sub-percent accuracy for the intensity of a near infrared water line at 10670 cm${}^{-1}$: experiment and analysis
• Thermophysical properties of argon gas from improved two-body interaction potential

Cited by in corpus (5)

• Third density and acoustic virial coefficients of helium isotopologues from ab initio calculations
• Path-integral calculation of the third dielectric virial coefficient of helium based on ab initio three-body polarizability and dipole surfaces
• Estimating complete basis set extrapolation error through random walk
• Revisiting the properties of superfluid and normal liquid ${}^4$He using ab initio potentials
• Third and fourth density and acoustic virial coefficients of neon from first-principles calculations