Bazı sıvı nadir-toprak geçiş metallerinin atomlararası potansiyelleri, yapısal ve atomik transport özellikleri
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Date
2003
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Trakya Üniversitesi
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info:eu-repo/semantics/openAccess
Abstract
ÖZET Bu çalışmada, sıvı f geçiş metallerinin hem yapı hem de atomik transport özelliklerini doğru olarak açıklayabilen atomlar-arası çiftler potansiyelleri ikinci mertebeden pseudopotansiyel teorisi ve Wills-Harrison model potansiyelleri kullanılarak elde edilmiştir. Literatürde f geçiş metalleri için iyi sonuç verdiği rapor edilen Bretonnet- Silbert yerel elektron-iyon potansiyeli ile Aschroft EC potansiyeli, Yerel Heine Abarenkov elektron-iyon potansiyelleri farklı ekranlama fonksiyonları kullanılarak sıvı f geçiş metallerinin etkin çiftler potansiyelleri standart pseudopotansiyel teorisi ile elde edilmiştir. Ayrıca sp bağlı metallere iyi uygulanabilen ve metalik atom gruplarında iyi çalışan Fiolhais potansiyelleri sıvı f geçiş metalleri için paremetrize edilmektedir. Analitik Pettifor-Ward atomlar-arası potansiyel yaklaşımı yukarıda verilen yerel pseudopotansiyeller kullanılarak f geçiş metallerine genişletilmektedir. Basit metal yaklaşımında kullanılan elektron-iyon potansiyelleri Wills-Harrison (WH) model potansiyellerinin s bandı katkısı olarak ele alınmış f geçiş metallerinin WH model potansiyelleri için Karmakar-Joarder (KJ) formu ile Singh formları kullanılmış etkin çiftler potansiyelleri elde edilmiştir. Atomlar-arası etkin çiftler etkileşme potansiyelleri sıvı yapısına integral denklem yaklaşımlarından Varyasyonel Hypernetted Chain integral denklem yaklaşımı (VMHNC) ile bağlanmaktadır. Ayrıca sıvıhal pertürbasyon metodlarından GB ve WC A metodu ile sıvı yapılan hesaplanmıştır. İncelenen sistemlerin yapısal özellikleri kullanılarak sıvı f geçiş metallerinin Atomik Transport (taşınma) özelliklerinden Difüzyon katsayısı, Viskozite gibi özellikleri ile Fazladan Entropi toplam Entropi gibi termodinamik büyüklükleri de hesaplanmıştır. Bu tezde sıvı f geçiş metallerinin hem yapı hem de atomik transport özelliklerini en iyi veren atomlar-arası potansiyel yaklaşımı tartışılmaktadır.
ABSTRACT THE INTERATOMIC PAIR POTENTIALS, STRUCTURAL AND ATOMIC TRANSPORT PROPERTIES OF SOME LIQUID RARE EARTH TRANSITION METALS In this work, the interatomic pair potentials are obtained by using the second order pseudopotential theory and Wills-Harrison model potentials which can accurately explain both the structures and the atomic transport properties of the liquid f transition metals. The Bretonnet-Silbert local electron-ion potential with the Aschroft EC potential, the local Heine Abarenkov electron-ion potentials, of which are reported in the literature that they give good results for the f transition metals, are derived from the effective pairs potentials standard pseudopotential theory of the liquid f transition metals by using the different screening functions. In addition, the Fiolhais potentials, which can be applied to the sp bonding metals and work well in the metallic atom groups are being parameterized for the liquid f transition metals. The analytical Pettifor-Ward interatomic potential approximation is being extended to the f transition metals by using the local pseudopotentials which are given above.The electron-ion potentials that are used in the simple metal approximation are considered as the s band contribution of the Wills-Harrison (WH) model potentials. For the WH model potentials of the f transition metals, Karmakar- Joarder and Singh forms are used and the effective pairs potentials are derived. The interatomic effective pair interaction potentials are connected to liquid structure by means of Variational Hypernetted Chain integral equation (VMHNC) that is one of the integral equation approximations. Additionally, the liquid structures are calculated using GB and WCA methods which are from the liquid state perturbation methods. The atomic transport properties of liquid f transition metals, such as diffusion coefficient and viscosity, with excess entropy and total entropy which are from thermodynamic quantities are calculated. In this thesis, the interatomic potential approximation is being argued of that gives best both the structures and the atomic transport features of the liquid f transition metals.
ABSTRACT THE INTERATOMIC PAIR POTENTIALS, STRUCTURAL AND ATOMIC TRANSPORT PROPERTIES OF SOME LIQUID RARE EARTH TRANSITION METALS In this work, the interatomic pair potentials are obtained by using the second order pseudopotential theory and Wills-Harrison model potentials which can accurately explain both the structures and the atomic transport properties of the liquid f transition metals. The Bretonnet-Silbert local electron-ion potential with the Aschroft EC potential, the local Heine Abarenkov electron-ion potentials, of which are reported in the literature that they give good results for the f transition metals, are derived from the effective pairs potentials standard pseudopotential theory of the liquid f transition metals by using the different screening functions. In addition, the Fiolhais potentials, which can be applied to the sp bonding metals and work well in the metallic atom groups are being parameterized for the liquid f transition metals. The analytical Pettifor-Ward interatomic potential approximation is being extended to the f transition metals by using the local pseudopotentials which are given above.The electron-ion potentials that are used in the simple metal approximation are considered as the s band contribution of the Wills-Harrison (WH) model potentials. For the WH model potentials of the f transition metals, Karmakar- Joarder and Singh forms are used and the effective pairs potentials are derived. The interatomic effective pair interaction potentials are connected to liquid structure by means of Variational Hypernetted Chain integral equation (VMHNC) that is one of the integral equation approximations. Additionally, the liquid structures are calculated using GB and WCA methods which are from the liquid state perturbation methods. The atomic transport properties of liquid f transition metals, such as diffusion coefficient and viscosity, with excess entropy and total entropy which are from thermodynamic quantities are calculated. In this thesis, the interatomic potential approximation is being argued of that gives best both the structures and the atomic transport features of the liquid f transition metals.
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Fizik ve Fizik Mühendisliği, Physics and Physics Engineering
