Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lamb shift in radical-ion pairs produces a singlet-triplet energy
  splitting in photosynthetic reaction centers   Radical-ion pairs, fundamental for understanding photosynthesis and the avian
magnetic compass, were recently shown to be biological open quantum systems. We
here show that the coupling of the radical-pair's spin degrees of freedom to
its decohering vibrational reservoir leads to a shift of the radical-pair's
magnetic energy levels. The Lamb shift Hamiltonian is diagonal in the
singlet-triplet basis, and results in a singlet-triplet energy splitting
physically indistinguishable from an exchange interaction. This could have
significant implications for understanding the energy level structure and the
dynamics of photosynthetic reaction centers.

12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
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The categories of this paper are: q-alg
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The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
35
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: dg-ga
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The categories of this paper are: comp-gas