8,052 research outputs found
Magnetism and Mott Transition: A Slave-rotor Study
Motivated by the debate of spin-density-wave (SDW) versus local-moment (LM)
picture in the iron-based superconducting (FeSC) materials, we consider a
two-band orbital-symmetric Hubbard model in which there is robust Fermi surface
nesting at . We obtain the phase diagram of such system by a
mean-field slave-rotor approach, in which the Fermi surface nesting and the SDW
order are explicitly taken into account via a natural separation of scale
between the Hund's coupling and the Coulomb interaction. We find that for a
sizable range of Hund's coupling the Mott transition acquires a strong
first-order character, but there also exists a small range of stronger Hund's
coupling in which an enhancement of magnetization can be observed on the SDW
side. We interpret the former scenario as one in which a sharp distinction can
be drawn between LM and the SDW picture, and the latter scenario as one in
which signs of LM physics begin to develop in the metallic phase. It is
tempting to suggest that some FeSC materials are in the vicinity of the latter
scenario.Comment: 7 pages, 5 figures; v2: Added discussions on anisotropy in
renormalized hopping, clarifications and discussions with regard to orbital
order, new inset in Fig. 3(d), expanded and revised bibliography, plus other
minor revisions. Accepted to PR
Secondary water pore formation for proton transport in a ClC exchanger revealed by an atomistic molecular dynamics simulation
Several prokaryotic ClC proteins have been demonstrated to function as exchangers that transport both chloride ions and protons simultaneously in opposite directions. However, the path of the proton through the ClC exchanger and how the protein brings about the coupled movement of both ions are still unknown. In the present work, we demonstrate that a previously unknown secondary water pore is formed inside a ClC exchanger by using an atomistic molecular dynamics (MD) simulation. From the systematic simulations, it was determined that the glutamate residue exposed to the intracellular solution, E203, plays an important role as a trigger for the formation of the secondary water pore. Based on our simulation results, we conclude that protons in the ClC exchanger are conducted via a water network through the secondary water pore and we propose a new mechanism for the coupled transport of chloride ions and protons
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