Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The ground state of a spin-crossover molecule calculated by diffusion
  Monte Carlo   Spin crossover molecules have recently emerged as a family of compounds
potentially useful for implementing molecular spintronics devices. The
calculations of the electronic properties of such molecules is a formidable
theoretical challenge as one has to describe the spin ground state of a
transition metal as the legand field changes. The problem is dominated by the
interplay between strong electron correlation at the transition metal site and
charge delocalization over the ligands, and thus it fits into a class of
problems where density functional theory may be inadequate. Furthermore, the
crossover activity is extremely sensitive to environmental conditions, which
are difficult to fully characterize. Here we discuss the phase transition of a
prototypical spin crossover molecule as obtained with diffusion Monte Carlo
simulations. We demonstrate that the ground state changes depending on whether
the molecule is in the gas or in the solid phase. As our calculation provides a
solid benchmark for the theory we then assess the performances of density
functional theory. We find that the low spin state is always over-stabilized,
not only by the (semi-)local functionals, but even by the most commonly used
hybrids (such as B3LYP and PBE0). We then propose that reliable results can be
obtained by using hybrid functionals containing about 50% of exact-exchange.

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The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: nlin
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The categories of this paper are: nucl-th
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The categories of this paper are: dg-ga
1
The categories of this paper are: cs