Variational density matrix approach to the temperature-dependent elementary excitation spectrum of two-dimensional liquid {sup 4}He

Journal Article · Thu Feb 01 04:00:00 EST 1996 · Journal of Low Temperature Physics

OSTI ID:272744

Um, Chung-In; Kahng, Jae-Rok ^[1]; Yeon, Kyu-Hwang ^[2]; George, T F ^[3]

---

1. Korea Univ., Seoul (Korea, Republic of)
2. Chungbuk National Univ., Chung Buk (Korea, Republic of)
3. Washington State Univ., Pullman, WA (United States)

Using the variational density matrix method, the authors obtain a temperature-dependent elementary excitation spectrum for two-dimensional liquid {sup 4}He. For more precise results, they use a Jastrow-Feenburg type trial wave function and include the contribution of elementary diagrams within the hypernetted chain approximation. The behavior of the excitation spectrum as a function of the temperature and density in two dimensions is similiar to that of the bulk system, but has a smaller roton minimum. The roton minimum of the excitation spectrum decreases with increasing temperature and increases with increasing density at low densities but decreases at large densities. The results agree well with Monte Carlo calculations and are closer than previous theories to experimental measurements of {sup 4}He film adsorbed on substrates.

• OSTI ID: 272744
• Journal Information: Journal of Low Temperature Physics, Journal Name: Journal of Low Temperature Physics Journal Issue: 3-4 Vol. 102; ISSN JLTPAC; ISSN 0022-2291
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
COLLECTIVE EXCITATIONS
DENSITY MATRIX
HELIUM 4
ROTONS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
VARIATIONAL METHODS