Low-energy elementary surface excitations of symmetric films of liquid4He atT=0 K |
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Authors: | Leszek Szybisz |
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Affiliation: | (1) Laboratorio TANDAR, Departmento de Física, Comisión Nacional de Energía Atómica, Av. del Libertador 8250, RA-1429 Buenos Aires, Argentina;(2) Present address: The Carrera del Investigador Científico of the Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917, RA-1033 Buenos Aires, Argentina |
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Abstract: | It is known that low-energy elementary excitations of symmetric films of liquid4He atT=0 K are characterized by a momentum q parallel to the surface and may be described by bound states. We have evaluated wave functions and energies of these states for both best short-ranged and optimal long-ranged correlations. Quantities of physical interest may be expressed in terms of these eigenstates and, in particular, for very small momenta (q<0.2 Å–1) they are mainly determined by the contribution due to the lowest-lying one. We propose analytic expressions for the lowest-lying excitations and fluctuations in the long-wavelength limit. It is proved that in this limiting case, the excitation energy ![hstrok](/content/v630860t734q4203/xxlarge295.gif) LW(q) and the averaged static structure functionSLW(q) should go linearly to zero asq 0, whereas the averaged direct correlationXLWDg(q) should diverge at the origin as 1/q. It is shown that numerical solutions exhibit the expected long-wavelength behavior provided that optimal correlations are used. All these results are displayed in a series of figures and are discussed in detail. |
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Keywords: | 67.40.Db 67.70.+n 68.10.-m |
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