Optical properties of anatase and rutile TiO${}_{2}$ studied by GGA + U *

control of the optical properties of nanoparticles by laser fields

در این پایان نامه، درهمتنیدگی بین یک سیستم نقطه کوانتومی دوگانه(مولکول نقطه کوانتومی) و میدان مورد مطالعه قرار گرفته است. از آنتروپی ون نیومن به عنوان ابزاری برای بررسی درهمتنیدگی بین اتم و میدان استفاده شده و تاثیر پارامترهای مختلف، نظیر تونل زنی(که توسط تغییر ولتاژ ایجاد می شود)، شدت میدان و نسبت دو گسیل خودبخودی بر رفتار درجه درهمتنیدگی سیستم بررسی شده اشت.با تغییر هر یک از این پارامترها، در...

GGA+U description of lithium intercalation into anatase TiO2

We have used density-functional theory generalized gradient approximation GGA to study lithium intercalation at low concentration into anatase TiO2. To describe the defect states produced by Li doping a Hubbard “+U” correction is applied to the Ti d states GGA+U . Uncorrected GGA calculations predict LixTiO2 to be metallic with the excess charge distributed over all Ti sites, whereas GGA+U pred...

Formation enthalpies by mixing GGA and GGA + U calculations

Band alignment of rutile and anatase TiO2

The most widely used oxide for photocatalytic applications owing to its low cost and high activity is TiO2. The discovery of the photolysis of water on the surface of TiO2 in 19721 launched four decades of intensive research into the underlying chemical and physical processes involved2–5. Despite much collected evidence, a thoroughly convincing explanation of why mixed-phase samples of anatase ...

EXAFS Study of Rutile and Anatase

T w o crystallographic forms of TiC>2 (rutile and anatase) were subject to a n extended x r a y absorption fine structure study a t the K threshold of t i tanium. D a t a analysis was carried out b y Fourier methods and curve fitting techniques. Using the theoretical phases, T i 0 bond distances of 1.93(1) A were derived both for ruti le and anatase, as compared to the crystallographic values o...