Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the preservation of coherence in the electronic wavepacket of a
  neutral and rigid polyatomic molecule   We present various types of reduced models including five vibrational modes
and three electronic states for the pyrazine molecule in order to investigate
the lifetime of electronic coherence in a rigid and neutral system. Using an
ultrafast optical pumping in the ground state (1 1 A g ), we prepare a coherent
superposition of two bright excited states, 1 1 B 2u and 1 1 B 1u , and reveal
the effect of the nuclear motion on the preservation of the electronic
coherence induced by the laser pulse. More specifically, two aspects are
considered: the anharmonicity of the potential energy surfaces and the
dependence of the transition dipole moments (TDMs) with respect to the nuclear
coordinates. To this end, we define an ideal model by making three
approximations: (i) only the five totally symmetric modes move, (ii) which
correspond to uncoupled harmonic oscillators, and (iii) the TDMs from the
ground electronic state to the two bright states are constant (Franck-Condon
approximation). We then lift the second and third approximations by
considering, first, the effect of anharmonicity, second, the effect of
coordinate-dependence of the TDMs (first-order Herzberg- Teller contribution),
third, both. Our detailed numerical study with quantum dynamics confirms
long-term revivals of the electronic coherence even for the most realistic
model.

2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas