2-D phase transitions

✍ Scribed by Andrey Milchev

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 517 KB
• Volume: 28
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(83)85170-6

✦ Synopsis

A simple statistical-mechanical model which describes the thermodynamic properties of a system of spherically symmetrical particles adsorbed on a crystalline substrate. has been suggested. The present approach tackles both highelow density phase transitions (2-D condensation) as well as high(l) + high(2, 3) density phase transitions ("in registry" e" out of registry"). The theory allows for the following physically important properties of the system: (i) non-additivity of the lateral interactions betwmn the adatoms, (ii) coupling between vibrational and configurational properties of the adsorbed 2-D monolayer, (iii)competition between adatom-surfaceand adatom-adatom forces, (IV) the existence of misfit between the lattice constant of the surface and the characteristical atom spacing of the unperturbed adsorbate. Within the framework of the Mean Field Approximation (MFA) closed analytical expressions for the thermodynamic functions of the system are derived whereby the role of the effects quoted above (it-(iv) is clearly demonstrated. Some ofthese ctrects, eg the role of the non-additive nature of the interatomic forces, is even more pronounced, provided a more elaborated statistical treatment such as the Quasi-Classical Approximation (QCA) is employed. The method suggests a semquantitatlve description of observed experimental data.