5405

5065

كارشناسي ارشد

فيزيك

اصفهان: دانشگاه صنعتي اصفهان، دانشكده فيزيك

1389

[دوازده]،125ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

هادي اكبر زاده، مجتبي اعلائي

جواد هاشمي فر

14/6/89

داخلي: فرهاد شهبازي، خارجي: پيمان صاحب سرا

فيزيك

ID5065

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Quantum Monte Carlo Computations for a Graphene Layer Atoosa Zangeneh azangeneh@sepahan iut ac ir April 13 2010 Department of Physics Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi H Akbarzadeh akbarzad@cc iut ac ir M Alaei m alaei@cc iut ac ir Abstract In this thesis Quantum Monte Carlo QMC techniques applied to calculate electronic and struc tural properties of a single graphene sheet Our aim is to gain better accuracy than other current electronic structure methods such as Density Functional Theory DFT The computational time in QMC scales reasonably with size of system Also QMC can take into account electronic correlation very accurately Therefore QMC is a good candidate when a large system such as big molecules or crystal systems needs to be treated very accurately We used both DFT and QMC methods for graphene PWscf code was used for DFT calculations Then We feeded CASINO code with wave functions of PWscf Finally by using Variational Monte Carlo VMC the PWscf wavefunctions were improved to better trial wavefunctions To do this we added Jastrow factor to PWscf wavefunctions We needed to improve trial wavefunctions because of Di usion Monte Carlo DMC DMC method is the most accurate method in QMC and with better wavefunctions we can reduce errors in this method Also in VMC calculations we could guess the e ective length of electron electron correlation We compared DFT VMC and DMC results At the end we calculated cohesive energy of graphene within LDA GGA and DMC and compared them with experimental data Key Words graphene Variational Monte Carlo Di usion Monte Carlo DFT QMC VMC DMC PWscf CASINO

هادي اكبر زاده، مجتبي اعلائي

جواد هاشمي فر