Theory of quantum fluids

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1981

OSTI ID:6348339

Whitney, L R

The Euler-Lagrange ground state Jastrow and triplet-Feenberg calculations for liquid /sup 4/He are generalized to finite temperatures. The thermally excited states are constructed from the generalized Bijl-Feynman functions giving a quasiparticle model, in an occupation-number representation to 4th order in creation and destruction operators, which is approximately orthonormalized within certain truncations of the cumulant expansion of the static multiple density correlation functions. The Gibbs-Bogoliubov inequality, the basis of the T is not equal to 0 variational calculation, is applied to the 4th order Hamiltonian; three canonical transformations are developed to facilitate this calculation. Qualitative agreement with experiment from this microscopic calculation is obtained for the anomalous temperature dependence of the liquid structure function delta(K,T) which shows increasing short range order with increasing temperature below T lambda, and normal behavior above T lambda. Contrary to experiment, the roton-roton interaction in this model is repulsive. Semi-empirical calculations using the experimental single particle excitation spectrum as input suggest that significant improvement in the delta(K,T) calculation is possible if the attractive roton-roton interaction was to be incorporated in the model.

• Research Organization: Minnesota Univ., Minneapolis (USA)
• OSTI ID: 6348339
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
640460 -- Fluid Physics-- Other Quantum Fluids
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CANONICAL TRANSFORMATIONS
ENERGY LEVELS
EVEN-EVEN NUCLEI
EXCITED STATES
FLUIDS
FUNCTIONS
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MATHEMATICAL MODELS
NUCLEI
QUANTUM FLUIDS
STABLE ISOTOPES
STRUCTURE FUNCTIONS
TEMPERATURE EFFECTS
TRANSFORMATIONS