7909

7357

كارشناسي ارشد

ماده چگال

اصفهان: دانشگاه صنعتي اصفهان، دانشكده فيزيك

1391

نه،84ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

جواد هاشمي فر

مجتبي اعلايي

4/6/92

فيزيك

ID7357

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Studying the absoption spaectra of Agn and Agn mPdm n 9 m 1 2 using the octopus package based on time dependent density functional theory TDDFT Hojatollah Mokhtari Baghabrishami h mokhtari@ph iut ac ir 01 02 2013 Department of Physics Isfahan University of technology Isfahan 84156 83111 Iran Degree M Sc Language Persian Supervisor Dr S J Hashemifar hashemifar@cc iut ac ir Abstract In the present work we have studied the effect of alloying with one and two palladium atoms on the electronic properties and absorption spectra of the small silver nanoclusters According to the nature of the absorption phenomenon that is a time dependent quantum mechanical phenomenon we have used the time dependent density functional theory TDDFT in our calculations The calculations are performed using the Octopus Package This computational Package is produced based on the TDDFT It uses the pseudopotential approach and expands the wave functions and other respective quantities in the real space It should be noted that since this code has a serious problems to optimize the geometry of the structures we have used the Quantum ESPRESSO code for the relaxation of structures The obtained results for the absorption spectra are in good agreement with the available exper imental data We have seen a very strong peak in the absorption spectrum of the silver nanocl uster with six atoms hexamer that is the largest silver nanoclusters in two dimensions 2D We have attributed this peak to the high symmetry of their structures For Ag6 We realize that if we add the absorption spectra of more stable structure and first isomer of it the experiment al and computational results are comparable Hence we have concluded that there are both the more stable structure and its first isomer in the experimental sample of this nonocluster The r esults show that alloying with palladium increase the number of peaks and also some of them becoms wide Similarly it was observed that the d orbital of palladium atoms as a retaining wall causes a weak transition from the s orbital of silver to the conduction states This leads to weak the peaks with low energy Keywords Time dependent density functional theory Ag clusters AgPd clusters Octopus code absorption spectra degeneracyPDF created with pdfFactory trial version www pdffactory com

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