The photoabsorption spectra have been calculated for Sis and SilO （n ≤ 5） clusters using time-dependent density-function theory. Our studies suggest that Sin-1 O clusters are relatively stable than those of corresp...The photoabsorption spectra have been calculated for Sis and SilO （n ≤ 5） clusters using time-dependent density-function theory. Our studies suggest that Sin-1 O clusters are relatively stable than those of corresponding Sis clusters. Moreover, substantial differences are observed among the absorption spectra of different molecules in the energy region （0 - 8 eV）. Comparing two different exchange-correlation potentials, local-density and generalized-gradient approximations, both calculated optical spectra present the same spectral feature.展开更多
Based on Fermi’s golden rule and the theory of Boltzmann collision term approximation, the hole scattering mechanism ofstrained Si/(111)Si1 xGexwas established, including ionized impurity, acoustic phonon, non-polar ...Based on Fermi’s golden rule and the theory of Boltzmann collision term approximation, the hole scattering mechanism ofstrained Si/(111)Si1 xGexwas established, including ionized impurity, acoustic phonon, non-polar optical phonon and totalscattering rate models. It was found that the total scattering rate of the hole in strained Si/(111)Si1 xGexdecreased obviouslywith the increasing stress when energy was 0.04 eV. In comparison with one of the unstrained Si, the total hole scattering rateof strained Si/(111)Si1 xGexdecreased about 38% at most. The decreasing hole scattering rate enhanced the hole mobility instrained Si materials. The result could provide valuable references to the research on hole mobility of strained Si materials andthe design of PMOS devices.展开更多
Two stochastic models are derived for a susceptible-infectious-susceptible epidemic spreading through a metapopulation： a continuous time Markov chain （CTMC） model and an It6 stochastic differential equation （SDE...Two stochastic models are derived for a susceptible-infectious-susceptible epidemic spreading through a metapopulation： a continuous time Markov chain （CTMC） model and an It6 stochastic differential equation （SDE） model. The stochastic models are numerically compared. Close agreement suggests that computationally intense CTMC simulations can be approximated by simpler SDE simulations. Differential equations for the moments of the SDE probability distribution are also derived, the steady states are solved numerically using a moment closure technique, and these results are compared to simulations. The moment closure technique only coarsely approximates simulation results. The effect of model parameters on stability of the disease-free equilibrium is also numerically investigated.展开更多
基金supported by the National Natural Science Foundation of China and China Academy of Engineering Physics under Grant No. 10676025 (NSAF)
文摘The photoabsorption spectra have been calculated for Sis and SilO （n ≤ 5） clusters using time-dependent density-function theory. Our studies suggest that Sin-1 O clusters are relatively stable than those of corresponding Sis clusters. Moreover, substantial differences are observed among the absorption spectra of different molecules in the energy region （0 - 8 eV）. Comparing two different exchange-correlation potentials, local-density and generalized-gradient approximations, both calculated optical spectra present the same spectral feature.
基金supported by the National Ministries and Commissions(Grant Nos. 51308040203, 9140A08060407DZ0103 and 6139801)the Fundamental Research Funds for the Central Universities (Grant No.72105499)
文摘Based on Fermi’s golden rule and the theory of Boltzmann collision term approximation, the hole scattering mechanism ofstrained Si/(111)Si1 xGexwas established, including ionized impurity, acoustic phonon, non-polar optical phonon and totalscattering rate models. It was found that the total scattering rate of the hole in strained Si/(111)Si1 xGexdecreased obviouslywith the increasing stress when energy was 0.04 eV. In comparison with one of the unstrained Si, the total hole scattering rateof strained Si/(111)Si1 xGexdecreased about 38% at most. The decreasing hole scattering rate enhanced the hole mobility instrained Si materials. The result could provide valuable references to the research on hole mobility of strained Si materials andthe design of PMOS devices.
文摘Two stochastic models are derived for a susceptible-infectious-susceptible epidemic spreading through a metapopulation： a continuous time Markov chain （CTMC） model and an It6 stochastic differential equation （SDE） model. The stochastic models are numerically compared. Close agreement suggests that computationally intense CTMC simulations can be approximated by simpler SDE simulations. Differential equations for the moments of the SDE probability distribution are also derived, the steady states are solved numerically using a moment closure technique, and these results are compared to simulations. The moment closure technique only coarsely approximates simulation results. The effect of model parameters on stability of the disease-free equilibrium is also numerically investigated.
