Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ab initio molecular dynamics with nuclear quantum effects at classical
  cost: ring polymer contraction for density functional theory   Path integral molecular dynamics simulations, combined with an ab initio
evaluation of interactions using electronic structure theory, incorporate the
quantum mechanical nature of both the electrons and nuclei, which are essential
to accurately describe systems containing light nuclei. However, path integral
simulations have traditionally required a computational cost around two orders
of magnitude greater than treating the nuclei classically, making them
prohibitively costly for most applications. Here we show that the cost of path
integral simulations can be dramatically reduced by extending our ring polymer
contraction approach to ab initio molecular dynamics simulations. By using
density functional tight binding as a reference system, we show that our ab
initio ring polymer contraction (AI-RPC) scheme gives rapid and systematic
convergence to the full path integral density functional theory result. We
demonstrate the efficiency of this approach in ab initio simulations of liquid
water and the reactive protonated and deprotonated water dimer systems. We find
that the vast majority of the nuclear quantum effects are accurately captured
using contraction to just the ring polymer centroid, which requires the same
number of density functional theory calculations as a classical simulation.
Combined with a multiple time step scheme using the same reference system,
which allows the time step to be increased, our implementation is as fast as a
typical classical ab initio molecular dynamics simulation and 35$\times$ faster
than a full path integral calculation, while still exactly including the
quantum sampling of nuclei. This development thus offers a route to routinely
include nuclear quantum effects in ab initio molecular dynamics simulations at
negligible computational cost.

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The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
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The categories of this paper are: mtrl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: ao-sci
2
The categories of this paper are: math
16
The categories of this paper are: stat
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
18
The categories of this paper are: econ