Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lifshitz Transition and Nontrivial H-Doping Effect in Cr-based
  Superconductor KCr$_3$As$_3$H$_x$   We report the first-principles study on the H-intercalated Cr-based
superconductor KCr$_3$As$_3$H$_x$. Our results show a paramagnetic ground state
for KCr$_3$As$_3$H. The electronic structure consists of two
quasi-one-dimensional (Q1D) Fermi-surfaces and one 3D Fermi-surface which are
mainly contributed by Cr-d$_{z^2}$, d$_{x^2-y^2}$ and d$_{xy}$ orbitals. The
bare electron susceptibility shows a $\Gamma$-centered imaginary peak,
indicating possible ferromagnetic spin fluctuations. Upon moderate hole doping,
the system undergoes a Lifshitz transition, which may enhance the Q1D feature
of the system. The Bader charge analysis and electron localization functions
reveal a strong bonding nature of hydrogen in KCr$_3$As$_3$H, which results in
a nontrivial electron doping in KCr$_3$As$_3$H.

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The categories of this paper are: nucl-th
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The categories of this paper are: q-fin
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The categories of this paper are: math
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The categories of this paper are: funct-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: ao-sci
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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol