The electronic and magnetic properties of (Mn,N)-codoped ZnO are studied within the framework of the density functional theory, by using the Perdew–Burke–Ernzerhof form of generalized gradient approximation. Five geometrical configurations of Mn doped ZnO are investigated and antiferromagnetic (AFM) properties of Mn doped ZnO are demonstrated. Furthermore, by investigating 13 geometrical configurations, for (Mn,N)-codoped ZnO, the ground state is changed from no-metallic AFM to half-metallic ferromagnetic, which is due to the strong hybridization between N 2p and Mn 3d states. In addition, the most stable configurations are found to be –O–Mn–N–Mn–O–.
A first-principles study has been performed to calculate the electronic and optical properties of the SbxSn1−xO system. The simulations are based upon the method of generalized gradient approximations with the Perdew-Burke-Ernzerhof form in the framework of density functional theory. The supercell structure shows a trend from expanding to shrinking with the increasing Sb concentration. The increasing Sb concentration induces the band gap narrowing. Optical transition has shifted to the low energy range with increasing Sb concentration. Other important optical constants such as the dielectric function, reflectivity, refractive index, and electron energy loss function for Sb-doped SnO2 are discussed. The optical absorption edge of SnO2 doped with Sb also shows a redshift.
Virtualization makes virtual machine placement (VMP) one of the most important technology in cloud computing. An effective VMP algorithm can significantly improve resource utilization of physical machines (PMs) in cloud datacenters. In this paper, we propose a VMP algorithm based on weighted PageRank (WPRVMP), which pursued to minimize the number of active PMs and improve the total resource utilization of all PMs in cloud datacenters. The impact of unplaced virtual machines (VMs) in the VMP process on the placement results, and the impact of VMP on the total resource utilization of all PMs are considered in this algorithm, to avoid the algorithm to fall into local optimal solution. In the process of selecting PM for each VM, the number of unplaced VMs of different types in the VMP process is considered in WPRVMP by weighted. The weighted PageRank algorithm is used to measure the possibility of a PM making full use of resources under different VMP conditions. The algorithm then ranks PMs according to the impact of the given VM is placed on each PM on the maximum resource utilization of all PMs, and places the VM based on the ranking results. Experimental results show that our algorithm is superior to other algorithms in reducing the number of active PMs and improving the resource utilization of PMs.
Electronic structure and optical properties of the zinc-blende InxGa1−xNyAs1−y system are calculated from the first-principles. Some relative simulations are performed using CA-PZ form of local density approximation in the framework of density functional theory. The supercell of intrinsic GaAs is calculated and optimized by using different methods, and the LDA-CA-PZ gives the most stable structure. The band gap of InxGa1−xAs tends to decrease with the increasing In concentration. For the case of In0.0625Ga0.9375NyAs1−y, the band gap will show slight difference when N concentration is larger than 18.75%. The optical transition of In dopant in GaAs exhibits a red shift, while it is a blue shift for the N dopant in InGaAs. Besides, dielectric function, reflectivity, refractive index and loss function in different doping model of InxGa1−xNyAs1−y are also discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.