9336

692 دكتري

دكتري

فيزيك

اصفهان: دانشگاه صنعتي اصفهان،دانشكده فيزيك

1393

[ده]،137ص.:مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

هادي اكبرزاده، جواد هاشمي فر

يوشي هيرا گودا

8/9/93

حسن سبزيان، حسين فرخ پور

فرهاد فضيله

فيزيك

ID692 دكتري

First principles investigation of two novel structures remarkable for environmental issues Y2Fe14B hard magnet crystal and Ag8 nanocatalyst Zahra torbatian z torbatian@ph iut ac ir Date of Submission 2014 9 7 Department of Physics Isfahan University of Technology Isfahan 84156 83111 Iran Degree PhD Language PersianSupervisors Dr Hadi Akbarzadeh akbarzad@cc iut ac ir Dr S Javad Hashemifar hashemifar@cc iut ac irAbstract In this project we use density functional computation to investigate physical properties of somematerials that may be useful to reduce environmental problems Spin density functional theory relativisticKohn Sham equations and time dependent density functional theory are used for our calculations In the first part we investigate the structural electronic and magnetic properties of Y 2Fe14B a newpermanent magnet based on rare earth iron and boron The most important property of these newpermanent magnets is its strong anisotropy Hard magnets are promising to improve the efficiency of allhybrid and electric cars and hence reduce carbon dioxide emission and air pullution From fundamentalpoint of view Y2Fe14B is a suitable target for studying the effects of strain on itinerant d electrons Incontrast with localized f electrons because Y is a prototypical f 0 example of rare earth elements Wecalculated the magnetic anisotropy energy by two different methods In the first method full self consistentcalculations in the presence of spin orbit coupling are performed for calculation of the magnetic anisotropyenergy In the second approach the spin orbit interaction is considered as a perturbation to the scalarrelativistic Hamiltonian and by using the second order perturbation theory the magnetic anisotropy of thesecrystals is determined with much lower computational cost compared with the first method and with anacceptable accuracy In the second part of project we determined the most stable structural isomers of the neutral Ag8cluster For better understanding of the relative stability of different structures of Ag 8 the structural electronic topological and optical properties were calculated Also the many body based GW correctionwas applied for accurate description of the highest occupied HOMO and the lowest unoccupied LUMO molecular orbital levels Then adsorption of the toxic CO NO and HCN molecules on the Td and D2d structures of theneutral Ag8 cluster was investigated The obtained adsorption energies fall in the range of physicaladsorption physisorption The calculation of charge distribution by using Bader theory of atoms inmolecules indicate a charge transfer from Ag8 to CO and NO molecules while no significant charge transferwas observed in the HCN Ag8 system Also the stable adsorption sites occur on the atoms which havecontribution to both HOMO and LUMO Also we calculated the absorption spectra of the molecule Ag8complexes and the pristine Ag8 The results show that silver nanocluster can be employed as catalyst andoptical sensor for NO molecule Keywords Magnetic anisotropy spin orbit interaction topology of electronic charge density silver nanocluster Many body GW correction

هادي اكبرزاده، جواد هاشمي فر

يوشي هيرا گودا

حسن سبزيان، حسين فرخ پور