Local ordering in dilute ortho-para-hydrogen mixtures at low temperatures

1988 ◽  
Vol 72 (1-2) ◽  
pp. 1-24 ◽  
Author(s):  
C. M. Edwards ◽  
D. Zhou ◽  
Y. Lin ◽  
N. S. Sullivan
Keyword(s):  
Low Temperatures ◽  
Para Hydrogen ◽  
Local Ordering ◽  
Hydrogen Mixtures

Orientational order–disorder transitions in solid hydrogen

1988 ◽  
Vol 66 (4) ◽  
pp. 908-914 ◽  
Author(s):  
N. S. Sullivan
Keyword(s):  
Orientational Order ◽  
Para Hydrogen ◽  
Local Ordering ◽  
Molecular Alignments ◽  
Hydrogen Mixtures ◽  
The Mean ◽  
Orientational Ordering ◽  
Quantum Rotors ◽  
Long Range Ordering ◽  
Continuous Freezing

We discuss the orientational ordering in solid ortho–para hydrogen mixtures. Following a brief sketch of the properties of the ortho and para hydrogen modifications and the long-range ordering of an assembly of J = 1 quantum rotors (ortho-H2), we consider the nature of the purely local ordering seen in random dilute ortho–para mixtures. Measurements of the quasi-static glass order parameter and the mean correlation time for the molecular alignments are interpreted in terms of a rapid but continuous freezing of the orientational fluctuations.

scholarly journals The chemical constant of hydrogen vapour and the entropy of crystalline hydrogen

1931 ◽  
Vol 130 (813) ◽  
pp. 367-379 ◽  
Keyword(s):  
Vapour Pressure ◽  
Low Temperatures ◽  
Hydrogen Gas ◽  
Para Hydrogen ◽  
Bose Statistics ◽  
Hydrogen Molecules ◽  
Quantum Numbers ◽  
A Value ◽  
Classical Statistics ◽  
Chemical Constant

In a paper called "The Chemical constant of Hydrogen Vapour and the failure of Nernst's Heat Theorem," R. H. Fowler has investigated the vapour pressure of hydrogen crystals at low temperature; taking account of the existence of two sorts of hydrogen molecules, namely, ortho-hydrogen with even rotational quantum numbers and para-hydrogen with odd rotational quantum numbers, which retain their individuality over long periods at very low temperatures. By the use of the classical statistics, he was able to show that at very low temperatures hydrogen, as obtained by cooling hydrogen gas from ordinary temperatures, ought to have very nearly the experimentally observed chemical constant. Since the theory of the specific heat of hydrogen yielded correct values at low temperatures, it followed that at ordinary temperatures also his theory would yield a correct value for the chemical constant. Finally from the form of the partition function for hydrogen gas, Fowler attempted to obtain inferences concerning the validity of Nernst's heat theorem. By the use of the classical statistics fairly accurate results were obtained. But we shall find that when we make use of the Einstein-Bose statistics-the correct statistics for an assembly of hydrogen moleclues-a result will be obtained for the vapour pressure of hydrogen crystals at low temperatures which will furnish a value for the chemical constant of hydrogen in even closer agreement with experiment than Fowler's result.

Photooxidation of Trimethyl Phosphite in Nitrogen, Oxygen, and para-Hydrogen Matrixes at Low Temperatures

2017 ◽  
Vol 121 (10) ◽  
pp. 2121-2131 ◽  
Author(s):  
N. Ramanathan ◽  
K. Sundararajan ◽  
R. Gopi ◽  
K. Sankaran
Keyword(s):  
Low Temperatures ◽  
Trimethyl Phosphite ◽  
Para Hydrogen

scholarly journals THE PHYSICS OF LIQUID PARA-HYDROGEN

2006 ◽  
Vol 20 (30n31) ◽  
pp. 5035-5046 ◽  
Author(s):  
THOMAS LINDENAU ◽  
MANFRED L. RISTIG ◽  
KLAUS A. GERNOTH ◽  
JAVIER DAWIDOWSKI ◽  
FRANCISCO J. BERMEJO
Keyword(s):  
Experimental Data ◽  
Low Temperatures ◽  
Normal Phase ◽  
Para Hydrogen ◽  
Boson Systems ◽  
Path Integral Monte Carlo ◽  
Fundamental Interest ◽  
Hydrogen Molecules ◽  
Thermodynamic Phase ◽  
Theoretical Results

Macroscopic systems of hydrogen molecules exhibit a rich thermodynamic phase behavior. Due to the simplicity of the molecular constituents a detailed exploration of the thermal properties of these boson systems at low temperatures is of fundamental interest. Here, we report theoretical and experimental results on various spatial correlation functions and corresponding distributions in momentum space of liquid para-hydrogen close to the triple point. They characterize the structure of the correlated liquid and provide information on quantum effects present in this Bose fluid. Numerical calculations employ Correlated Density-Matrix (CDM) theory and Path-Integral Monte-Carlo(PIMC)simulations. A comparison of these theoretical results demonstrates the accuracy of CDM theory. This algorithm therefore permits a fast and efficient quantitative analysis of the normal phase of liquid para-hydrogen. We compare and discuss the theoretical results with available experimental data.

QUANTUM BOLTZMANN LIQUIDS

2007 ◽  
Vol 21 (13n14) ◽  
pp. 2157-2168 ◽  
Author(s):  
K. A. GERNOTH ◽  
MANFRED L. RISTIG ◽  
THOMAS LINDENAU
Keyword(s):  
Low Temperatures ◽  
Matrix Theory ◽  
Quantum Mechanical ◽  
Para Hydrogen ◽  
Path Integral Monte Carlo ◽  
Quantum Fluid ◽  
Interparticle Forces ◽  
Thermodynamic Conditions ◽  
Density Matrix Theory ◽  
Phase Phase

We study homogeneous normal systems of bosons under the influence of interparticle forces with a strongly repulsive component at short relative particle-particle distances. The repulsion prevents short-ranged exchange between the bosonic constituents in the quantum fluid. Consequently, the bosons remain distinguishable at temperatures far below the classical high-temperature regime. At these low temperatures such fluids and liquids display nevertheless distinct quantum effects due to quantum-mechanical phase-phase correlations. Typical examples are liquid para-hydrogen and fluid 4 He under certain thermodynamic conditions. The study employs Correlated Density-Matrix theory and Path-Integral Monte-Carlo simulations.

RADIAL DISTRIBUTION AND LIQUID STRUCTURE FUNCTION FOR LIQUID PARA-HYDROGEN AT LOW TEMPERATURES

2006 ◽  
Vol 20 (30n31) ◽  
pp. 5057-5060 ◽  
Author(s):  
KLAUS A. GERNOTH ◽  
MATTHEW J. HARRISON ◽  
MANFRED L. RISTIG
Keyword(s):  
Monte Carlo ◽  
Structure Function ◽  
Radial Distribution ◽  
Low Temperatures ◽  
Quantum Monte Carlo ◽  
Matrix Theory ◽  
Liquid Structure ◽  
Para Hydrogen ◽  
Density Matrix Theory ◽  
Theoretical Results

We present theoretical results for the radial distribution function g(r) and the static liquid structure function S(k) of liquid para-hydrogen at low temperatures. The results have been obtained via quantum Monte Carlo Path Integral simulations, classical Monte Carlo calculations, and correlated density matrix theory.

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