Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum Phase Transitions in Spin Systems   We discuss the influence of strong quantum fluctuations on zero-temperature
phase transitions in a two-dimensional spin-half Heisenberg system. Using a
high-order coupled cluster treatment, we study competition of magnetic bonds
with and without frustration. We find that the coupled cluster treatment is
able to describe the zero-temperature transitions in a qualitatively correct
way, even if frustration is present and other methods such as quantum Monte
Carlo fail.

1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas