Gömülü atom metodu ile sıvı HCP nadir toprak metallerinin atomlararası etkileşme potansiyelleri, sıvı yapıları ve bazı termodinamik özellikleri
The interatomic pair potentials, structure and thermodynamic properties of liquid HCP rare-earth metals using the embedded atom method
Yazar: SÜLEYMAN KALAYCI
Danışman: PROF.DR. SERAP DALGIÇ
Trakya Üniversitesi / Fen Bilimleri Enstitüsü / Fizik Ana Bilim Dalı
Derece: Yüksek Lisans, 2005
Konu: Fizik ve Fizik Mühendisliği = Physics and Physics Engineering

Özet:
iÖZETBu çalismada, sivi hcp nadir toprak geçis metallerinin yapisal ve termodinamiközelliklerini dogru olarak açiklayabilen atomlar arasi etkin çiftler potansiyellerinin,Gömülü Atom Metodu (GAM) ile elde edilmesi amaçlanmistir. Bu amaçla literatürdehcp geçis metalleri için kati özellikleri fit edilerek parametrize edilen farkli GömülüAtom Metodlari ele alinmis, Zhang-Quyang Gömülü Atom Metodu (ZQ-GAM), Hu-Xu, Hu-Zhang, Hu-Deng'in Analitik Yeniden Düzenlenmis Gömülü Atom Metodlari(AYDGAM) ve Chen-Xu GAM ile çalisilmistir. S. S. Dalgiç vd. tarafindan fcc sivigeçis metallerinin Gömülü Atom Metodu hesaplamalari için önerilmis olanparametrizasyon metodu hcp yapisindaki bazi nadir toprak metalleri, Pr, Nd, Gd, Tb,Dy, Ho, Er ile hcp geçis metallerinden Be, Mg, Sc, Y, La, Ti, Zr, Co' a dauygulanmistir. ZQ-GAM, Hu-Xu AYDGAM, Hu-Zhang AYDGAM, Hu-DengAYDGAM ve Chen-Xu GAM potansiyel fonksiyonlari önerilen parametrizasyonmetodu kullanilarak hesaplanmistir.Ayrica Gömülü Atom Metodunda Finnis-Sinclair (FS) Efektif Çiftler PotansiyelYaklasimi kullanilarak, ilk kez AYDGAM metodlari için FS yaklasimi gelistirilmis,enerji düzeltme terimlerinin de yer aldigi iki farkli FS efektif potansiyel metodu ileçalisilmistir.Hesaplanan Atomlar - arasi etkin çiftler potansiyelleri, sivi yapi teorilerindenVaryasyonel Hypernetted Chain (VMHNC)'nin giris datasi olarak kullanilmis,incelenen sistemlerin ergime noktalari civarindaki statik yapi faktörleri S(q) ve çiftlerdagilim fonksiyonlari g(r) hesaplanarak deneysel sonuçlar ile karsilastirilmistir. Eldeedilen yapisal özellikler ile sivi hcp geçis metallerinin iç enerji, Helmholtz serbestlikenerjisi ve entropileri hesaplanmis deneysel veriler ile karsilastirilmistir.

Abstract:
iiSUMMARYIn the present work, the interatomic effective pair potentials which are capableof predicting both the structural and thermodynamic properties of the liquid hcp rare-earth metals have been obtained using the embedded atom method (EAM). For thispurpose, the different versions of EAM model for the hcp metals which wereparameterised by fitting the solid state properties in the literature have been taken intoaccount. It has been studied with the Zhang-Quyang embedded atom method (ZQ-EAM), the Analytical Modified Embedded Atom Method (AMEAM) of Hu-Xu, Hu-Zhang, Hu-Deng and Chen-Xu EAM method. The parameterisation method proposedby S.S. Dalgic and co-workers for the EAM calculations of fcc liquid metals has beenapplied to hcp rare-earth metals such as Pr, Nd, Gd, Tb, Dy, Ho, Er and some hcptransition metals such as Be, Mg, Sc, Y, La, Ti, Zr, Co. The potential functions of theEAM models have been computed with this proposed parameterisation method.On the other hand, the Finnis-Sinclair (FS) effective pair potential approach inthe EAM has been used and extended to AMEAM calculations for the first time in theliterature. It has been studied with the two different FS approaches which include theenergy correction terms of AMEAM.The interatomic effective pair interaction potentials are used as input data for thevariational modified hypernetted chain (VMHNC) integral equation approximationwhich is one of the liquid state theories. The static structure factors and the pairdistributions of the investigated systems at near their melting points are computed andcompared with the experimental data. The computed structural properties have beenused in order to obtain the thermodynamic properties of the liquid hcp metals such asinternal energy, Helmholtz free energy, entropy and compared with experimental dataand the theoretical results those obtained by others.