Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Tunneling-splittings from path-integral molecular dynamics using a
  Langevin thermostat   We report an improved method for the calculation of tunneling splittings
between degenerate configurations in molecules and clusters using path-integral
molecular dynamics (PIMD). Starting from an expression involving a ratio of
thermodynamic density matrices at the bottom of the symmetric wells, we use
thermodynamic integration with molecular dynamics simulations and a Langevin
thermostat to compute the splittings stochastically. The thermodynamic
integration is performed by sampling along the semiclassical instanton path,
which provides an efficient reaction coordinate as well as being physically
well-motivated. This approach allows us to carry out PIMD calculations of the
multi-well tunnelling splitting pattern in water dimer, and to refine previous
PIMD calculations for one-dimensional models and malonaldehyde. The large
(acceptor) splitting in water dimer agrees to within 20% of benchmark
variational results, and the smaller splittings are within 10%.

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The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex