6,341 research outputs found
Correlation effects in the electronic structure of the Ni-based superconducting KNi2S2
The LDA plus Gutzwiller variational method is used to investigate the
groundstate physical properties of the newly discovered superconducting KNi2S2.
Five Ni-3d Wannier-orbital basis are constructed by the density-functional
theory, to combine with local Coulomb interaction to describe the normal state
electronic structure of Ni-based superconductor. The band structure and the
mass enhanced are studied based on a multiorbital Hubbard model by using
Gutzwiller approximation method. Our results indicate that the correlation
effects lead to the mass enhancement of KNi2S2. Different from the band
structure calculated from the LDA results, there are three energy bands across
the Fermi level along the X-Z line due to the existence of the correlation
effects, which induces a very complicated Fermi surface along the X-Z line. We
have also investigated the variation of the quasi-particle weight factor with
the hole or electron doping and found that the mass enhancement character has
been maintained with the doping.Comment: 12 pages, 6 figure
The Error Control Methods of Information System in Sensor Networks
Information System Error Discovery took a lot of interests of information system experts. Indeed, this concept has been interpreted in more than one way. This paper describes the connections between 1) the Field-to-Scope Proportion and the Identifying and Managing way of Error Discovery and 2) the (Transmission, Influence and Implementing) TII model and Error Scope. The main goal of the work described here, is to seek deeper understanding of Error Discovery in general and, at last, to find easier ways of confirming it. Second, in this paper we try to model the TII evaluating using Work Expressing System which is Relational Graph. We also use this process model to present the relationship between Error Discovery, TII, (Field-To-Scope Proportion) FSP and Error Scope. After explaining the relationship between Semantic Error and Error Discovery, we improve the Relational Graph model by adding standard. We then offer instructions of the Relational Graph
Vibronic fine structure in the nitrogen 1s photoelectron spectra from Franck-Condon simulations II: Indoles
The vibronic coupling effect in nitrogen 1s X-ray photoelectron spectra (XPS)
was systematically studied for a family of 17 bicyclic indole molecules by
combining Franck-Condon simulations (including the Duschinsky rotation effect)
and density functional theory. The simulated vibrationally-resolved spectra of
4 molecules agree well with available experiments. Reliable predictions for
this family further allowed us to summarize rules for spectral evolution in
response to three types of common structural changes (side chain substitution,
CHN replacement, and isomerization). Interestingly, vibronic
properties of amine and imine nitrogen are clearly separated: they show
negative and positive ZPE (zero-point vibration energy of the
core-ionized with respect to the ground state), respectively, indicating
flatter and steeper PESs induced by the N 1s ionization; amine N's show
stronger mode mixing effects than imine N's; the 1s ionizations on two types of
nitrogens led to distinct changes in local bond lengths and angles. The rules
are useful for a basic understanding of vibronic coupling in this family, and
the precise spectra are useful for future reference and data mining studies
Vibrationally-resolved X-ray spectra of diatomic systems: Time-independent and time-dependent simulations
We systematically investigated vibronic coupling effects in X-ray spectra of
diatomic systems using time-independent (TI) and time-dependent (TD) methods.
Under the TI framework, we studied 5 systems (N, N, NO, CO,
CO) in their lowest C/N/O 1s excited or ionized states, generating 10 X-ray
absorption (XAS) or photoelectron (XPS) spectra using density functional theory
(DFT) with two pure (BLYP, BP86) and two hybrid (B3LYP, M06-2X) functionals.
Excellent agreement between theoretical and experimental spectra was found in
most systems, except that in O1s XAS of CO and NO, intensities of
higher-energy peaks were underestimated. We established a connection between
their complex vibronic structures and the significant geometrical changes
induced by the O1s hole. Functional dependence in diatomic systems is generally
more pronounced than in polyatomic ones. In all examined cases, pure
functionals exhibit better or similar spectral accuracy to hybrid functionals,
attributed to superior prediction accuracy in bond lengths and vibrational
frequencies. With the TD wavepacket method, we simulated vibrationally-resolved
XAS of CO, NO, and CO using potential energy curves (PECs) generated at
both DFT and multiconfigurational levels. Both TD and TI generate similar C/O
1s XAS spectra of CO. For O1s XAS of NO and CO, TD calculations
significantly improved the corresponding TI results, demonstrating sensitivity
to the anharmonic effect and the PEC quality. TI and TD approaches are
complementary, with practical applications depending on the ease and accuracy
of excited-state geometry optimization or PEC scanning, and the significance of
anharmonicity. DFT with pure functionals is recommended for diatomic
calculations due to its easy execution and reliable accuracy. TI is optimal for
most scenarios, but TD is needed for problems with strong anharmonic effects.Comment: 11 figure
Euphorbia factor L8: a diterpenoid from the seeds of Euphorbia lathyris
The title compound [systematic name: (2S*,3S*,4R*,5R*,9S*,11S*,15R*)-5,15-diacetoxy-3-nicotinoyloxy-14-oxolathyra-6(17),12(E)-diene], C30H37NO7, was isolated from the seeds of Euphorbia lathyris. The tricyclic diterpenoid molecule contains an 11-membered ring, a five-membered ring exhibiting an envelope conformation and a three-membered ring. The 11-membered ring is cis-fused with the three-membered ring and trans-fused with the five-membered ring
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