Calculation of the He-II quasiparticle spectrum by the method of collective variables
Abstract
The method of collective variables (MCV) has been used to calculate the logarithm of the He-II ground-state wave function, ln(Psi0), to an accuracy of a first correction to the Jastrow function and, in a second approximation, the wave function Psik of the first excited state and the He-II quasiparticle spectrum. The functions Psi0 and Psik were found as the eigenfunctions of the N-particle Schro"dinger equation, and the function Psi0 was connected to the structure factor of He-II, using the Vakarchuk equation. The model does not contain any fitting parameter or function. The quasiparticle spectrum calculated numerically agrees well with the experiment. Our solution improves the result obtained early by Yukhnovskyi and Vakarchuk.
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