Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Probing anharmonic phonons by quantum correlators: A path integral
  approach   We devise an efficient scheme to determine vibrational properties from Path
Integral Molecular Dynamics (PIMD) simulations. The method is based on
zero-time Kubo-transformed correlation functions and captures the anharmonicity
of the potential due to both temperature and quantum effects. Using analytical
derivations and numerical calculations on toy-model potentials, we show that
two different estimators built upon PIMD correlation functions fully
characterize the phonon spectra and the anharmonicity strength. The first
estimator is associated with force-force quantum correlators and gives access
to the fundamental frequencies and thermodynamic properties of the quantum
system. The second one is instead connected to displacement-displacement
correlators and probes the lowest-energy phonon excitations with high accuracy.
We also prove that the use of generalized eigenvalue equations, in place of the
standard normal mode equations, leads to a significant speed-up in the PIMD
phonon calculations, both in terms of faster convergence rate and smaller
time-step bias. Within this framework, using ab initio PIMD simulations, we
compute phonon dispersions of diamond and of the high-pressure I41/amd phase of
atomic hydrogen. We find that, in the latter case, the anharmonicity is
stronger than previously estimated and yields a sizeable red-shift in the
vibrational spectrum of atomic hydrogen.

6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con