Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum Monte Carlo calculations of the structural properties and the
  B1-B2 phase transition of MgO   We report diffusion Monte Carlo (DMC) calculations on MgO in the rock-salt
and CsCl structures. The calculations are based on Hartree-Fock
pseudopotentials, with the single-particle orbitals entering the correlated
wave function being represented by a systematically convergeable cubic-spline
basis. Systematic tests are presented on system-size errors using periodically
repeating cells of up to over 600 atoms. The equilibrium lattice parameter of
the rock-salt structure obtained within DMC is almost identical to the
Hartree-Fock result, which is close to the experimental value. The DMC result
for the bulk modulus is also in good agreement with the experimental value. The
B1-B2 transition pressure (between the rock-salt and CsCl structures) is
predicted to be just below 600 GPa, which is beyond the experimentally
accessible range, in accord with other predictions based on Hartree-Fock and
density functional theories.

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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: q-fin
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: stat
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The categories of this paper are: nucl-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: math-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: cs
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The categories of this paper are: eess