Theory of Solid Hydrogen Mixture. I. Distribution of Local Order Parameters, NMR Line Shapes and Relaxation Times
Abstract
The orthopara mixture of solid H_{2} is studied theoretically for fcc lattices of finite size, assuming EQQ interaction. The excitation spectrum is calculated by using the Hartree groundstate obtained numerically. The lowest excitation energy decreases with decrease of ortho concentration X, and vanishes at X∼0.55. The distribution of the local order parameters (LOP) is obtained in comparison with NMR line shape. Importance of the quantum effect is pointed out for the distribution of LOP which broadens rapidly with decrease of X. The relaxation time T_{1} is also studied as a function of NMR frequency shift, manifesting that orthoH_{2} with smaller value of order parameter relaxes more rapidly in the quadrupolar glass region.
 Publication:

Journal of the Physical Society of Japan
 Pub Date:
 October 1986
 DOI:
 10.1143/JPSJ.55.3618
 Bibcode:
 1986JPSJ...55.3618M
 Keywords:

 Line Shape;
 Nuclear Magnetic Resonance;
 Ortho Hydrogen;
 Para Hydrogen;
 Relaxation Time;
 Solidified Gases;
 Face Centered Cubic Lattices;
 Ground State;
 Hamiltonian Functions;
 Quadrupoles;
 Quantum Mechanics;
 Atomic and Molecular Physics