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Physical review. B, Solid state

Momentum distribution for two many-boson systems

Gary S. Grest

Published Jun 1, 1975• 2 citations
Publisher

Abstract

The momentum distribution $n(k)$ and condensate fraction $\frac{{N}_{0}}{N}$ for liquid helium and for a charged Bose gas are evaluated in perturbation theory through second order in $\frac{1}{\sqrt{N}}$. For liquid helium at normal vapor pressure, to this order in perturbation theory, we obtain unphysical, negative values for $n(k)$. This result will be discussed in detail.

DOI
10.1103/physrevb.11.4730

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The momentum distribution of a charged Bose gas at high density has been figured out as the function of the reduced wave number k up to the terms of order 1/N in the 1/N-expansion method of our theory of the density-phase operator approach. In the low momentum limit, besides the well-known term which diverges as k-2, it has been shown that there appears another term which diverges as k-1 together with several regular terms. For higher wave numbers than k = 0.1 the computation has been made by following the Monte Carlo integration method. Remarks have been made on the condensate fraction and on the higher order terms of order 1/N2.
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Progress of Theoretical Physics Vol. 56 No. 1 (1976) pp. 16-30 Momentum Distribution of an Interacting Many-Boson System at High Density Toshiyuki Nishiyama Progress of Theoretical Physics Vol. 56 No. 2 (1976) pp. 415-434 Single Particle Aspects in a Collective Formalism for an Interacting Boson System Shuichiro Yamasaki, Takeji Kebukawa and Sigenobu Sunakawa Progress of Theoretical Physics Vol. 57 No. 1 (1977) pp. 12-27 Use of a Coherent-State Representation for a Many-Boson System at High Density Masakazu Tsujii and Toshiyuki Nishiyama Progress of Theoretical Physics Vol. 62 No. 5 (1979) pp. 1215-1224 Momentum Distribution of a Charged Bose Gas at High Density Toshiyuki Nishiyama and Yoiti Watanabe Progress of Theoretical Physics Vol. 64 No. 4 (1980) pp. 1248-1264 Bose-Einstein Condensation and the Canonical Conjugates to the Density Fluctuations Shuichiro Yamasaki and Masahiko Hirooka Progress of Theoretical Physics Vol. 64 No. 5 (1980) pp. 1565-1576 Momentum Distribution and Ground-State Energy of Liquid 4He at the Absolute Zero Temperature Toshiyuki Nishiyama and Yoiti Watanabe Progress of Theoretical Physics Vol. 68 No. 5 (1982) pp. 1482-1503 Quasi-Particle Description of a Degenerate System of Bosons Masahiko Hirooka and Shuichiro Yamasaki Progress of Theoretical Physics Vol. 84 No. 3 (1990) pp. 420-424 Condensate Fraction of a Charged Bose Gas at High Density Toshiyuki Nishiyama
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