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11.
Based on the spin generalized gradient approximation (σGGA) of the density functional theory (DFT), the structural, magnetic, and electronic properties of Mn-doped ZnO structure have thoroughly been investigated. It is found that the Mn atom prefers to substitute one of the Zn atoms, producing the energetically most stable configuration for the Mn-doped ZnO structure. Employing the Hubbard potential within the calculations suggests various changes and modifications to the structural, magnetic and electronic properties of the Mn-doped ZnO. Our calculations reveal that the local magnetic moment at the Mn site using the ordinary σGGA functional is 4.84 μB/Mn, which is smaller than that evaluated by including the Hubbard potential of 5.04 μB/Mn. Overall, the electronic band structure of the system, within the σGGA+U, is half-metallic, with metallic nature for the majority state and semiconducting nature for the minority state. Simulated scanning tunneling microscopy (STM) images for both unoccupied and occupied states indicate siginficant brightness on both Zn and Mn atoms and much brighter protrusions around the O atoms, respectively. 相似文献
12.
Xian-Ming Qin Zhao-Xian Yu Zhi-Yong Jiao Bing-Hao Xie 《International Journal of Theoretical Physics》2009,48(4):1098-1103
By using the Lewis-Riesenfeld invariant theory, we have studied the dynamical phase and the geometric phase in a two energy
level k-photon Jaynes-Cummings model with imaginary photon process. We find that the geometric phase in a cycle case is independent
of the frequency of the photon field, the coupling coefficient between photons and atoms, and the atom transition frequency.
We predict the physical effect of the geometric phase in the imaginary photon process may be measured. 相似文献
13.
This Letter investigates generalized function synchronization of continuous and discrete complex networks by impulsive control. By constructing the reasonable corresponding impulsively controlled response networks, some criteria and corollaries are derived for the generalized function synchronization between the impulsively controlled complex networks, continuous and discrete networks are both included. Furthermore, the generalized linear synchronization and nonlinear synchronization are respectively illustrated by several examples. All the numerical simulations demonstrate the correctness of the theoretical results. 相似文献
14.
Let A
1,…,A
N
be complex self-adjoint matrices and let ρ be a density matrix. The Robertson uncertainty principle
gives a bound for the quantum generalized covariance in terms of the commutators [A
h
,A
j
]. The right side matrix is antisymmetric and therefore the bound is trivial (equal to zero) in the odd case N=2m+1.
Let f be an arbitrary normalized symmetric operator monotone function and let 〈⋅,⋅〉
ρ,f
be the associated quantum Fisher information. Based on previous results of several authors, we propose here as a conjecture
the inequality
whose validity would give a non-trivial bound for any N∈ℕ using the commutators i[ρ,A
h
]. 相似文献
15.
《Journal of Pure and Applied Algebra》2023,227(2):107179
Let D be an integral domain and let be a torsion-free, ≤-cancellative, subtotally ordered monoid. We show that the generalized power series ring is a Krull domain if and only if D is a Krull domain and S is a Krull monoid. 相似文献
16.
17.
18.
It has been conjectured, on the basis of the gauge-gravity duality, that the ratio of the shear viscosity to the entropy density should be universally bounded from below by 1/4π in units of the Planck constant divided by the Boltzmann constant. Here, we prove the bound for any ghost-free extension of Einstein gravity and the field-theory dual thereof. Our proof is based on the fact that, for such an extension, any gravitational coupling can only increase from its Einstein value. Therefore, since the shear viscosity is a particular gravitational coupling, it is minimal for Einstein gravity. Meanwhile, we show that the entropy density can always be calibrated to its Einstein value. Our general principles are demonstrated for a pair of specific models, one with ghosts and one without. 相似文献
19.
20.
We determine curvature properties of pseudosymmetric type of certain warped product manifolds, and in particular of generalized Robertson–Walker spacetimes, with Einsteinian or quasi-Einsteinian fibre. 相似文献