First-principles studies of phase stability and the structural and dynamical properties of hydrogen-metal systems. Final report

Technical Report · Sat May 01 04:00:00 EDT 1993

DOI:https://doi.org/10.2172/10160400· OSTI ID:10160400

Chou, M Y

First-principles calculations were carried for the hydrogen-yttrium system using the pseudopotential method within the local density functional approximation (LDA). We have studied the nature of hydrogen pairing in the solid solution phase ({alpha}-YH{sub x}.) and identified the connection with electronic structure. The vibrational spectra, diffusion barrier, and migration path were also investigated. We have also studied the binding characteristics for different interstitial sites and the (420)-plane ordering of octahedral hydrogen in {beta}YH{sub 2+x} within the lattice gas model. Temperature-composition phase diagram was calculated by cluster variational method with the multibody interactions extracted from total energies of related ordered structures. Moreover, the discovery of Peierls distortions in YH{sub 3} explained the unusual hydrogen displacements found in neutron diffraction and the possibility of an excitonic insulating ground state was speculated. Several new improvements in the calculational techniques also been developed: Separable nonlocal pseudopotentials, scheme to calculate the full phonon spectrum, and distance dependent tight-binding parameters. The Ru(0001)-H system was also studied.

• Research Organization: Georgia Inst. of Tech., Atlanta, GA (United States). School of Physics
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG05-90ER45431
• OSTI ID: 10160400
• Report Number(s): DOE/ER/45431--3; ON: DE93016129
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204
ELECTRONIC STRUCTURE
PEIERLS-NABARRO FORCE
PHASE DIAGRAMS
PHASE STABILITY
PHYSICAL PROPERTIES
PROGRESS REPORT
RUTHENIUM HYDRIDES
YTTRIUM HYDRIDES