Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Many-body theory of positron binding in polyatomic molecules   Positrons bind to molecules leading to vibrational excitation and
spectacularly enhanced annihilation. Whilst positron binding energies have been
measured via resonant annihilation spectra for $\sim$90 molecules in the past
two decades, an accurate \emph{ab initio} theoretical description has remained
elusive. Of the molecules studied experimentally, calculations exist for only
6, and for these, standard quantum chemistry approaches have proved severely
deficient, agreeing with experiment to at best 25% accuracy for polar
molecules, and failing to predict binding in nonpolar molecules. The mechanisms
of binding are not understood. Here, we develop a many-body theory of
positron-molecule interactions and uncover the role of strong many-body
correlations including polarization of the electron cloud, screening of the
positron-electron Coulomb interaction by molecular electrons, and crucially,
the unique non-perturbative process of virtual-positronium formation (where a
molecular electron temporarily tunnels to the positron): they dramatically
enhance binding in polar molecules and enable binding in nonpolars. We also
elucidate the role of individual molecular orbitals, highlighting the
importance of electronic $\pi$ bonds. Overall, we calculate binding energies in
agreement with experiment (to within 1% in cases), and we predict binding in
formamide and nucleobases. As well as supporting resonant annihilation
experiments and positron-based molecular spectroscopy, the approach can be
extended to positron scattering and annihilation $\gamma$ spectra in molecules
and condensed matter, to provide fundamental insight and predictive capability
required to properly interpret materials science diagnostics, develop
antimatter-based technologies (including positron traps, beams and positron
emission tomography), and understand positrons in the galaxy.

23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an