A microscopic model of He-II. The method of collective variables

✍ Scribed by Maksim Tomchenko

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 148 KB
• Volume: 127
• Category: Article
• ISSN: 0167-7322
• DOI: 10.1016/j.molliq.2006.03.044

✦ Synopsis

We consider a microscopic model of He-II based on the method of collective variables. This method was first proposed by Bogoliubov and Zubarev and was later developed by Yukhnovskyy and Vakarchuk. We calculate the logarithm of the ground-state wave function of He-II to an accuracy of the first two corrections to the Jastrow function. We also calculate the wave function of the first excited phonon state and the quasiparticle spectrum of He-II in the second-order approximation. We consider two approaches: the first one is based on the model potential of interaction between He 4 atoms with one adjustable parameter; and the second approach involves the structure factor without any free parameters. The calculated quasiparticle spectrum agrees with the experiment.

Moreover, we calculate the amount of the one-particle and two particle condensates in He-II at T = 0 in the approximations of "one sum" and "two sums", without free parameters. In the more exact approximation of "two sums", we obtain that roughly 6% and 16% of helium atoms belong to the one-particle and two-particle condensates, respectively.