Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A re-examination of antiferroelectric PbZrO$_3$ and PbHfO$_3$: an
  80-atom $Pnam$ structure   First principles density functional theory (DFT) simulations of
antiferroelectric (AFE) PbZrO$_3$ and PbHfO$_3$ reveal a dynamical instability
in the phonon spectra of their purported low temperature $Pbam$ ground states.
This instability doubles the $c$-axis of $Pbam$ and condenses five new small
amplitude phonon modes giving rise to an 80-atom $Pnam$ structure. Compared
with $Pbam$, the stability of this structure is slightly enhanced and highly
reproducible as demonstrated through using different DFT codes and different
treatments of electronic exchange & correlation interactions. This suggests
that $Pnam$ is a new candidate for the low temperature ground state of both
materials. With this finding, we bring parity between the AFE archetypes and
recent observations of a very similar AFE phase in doped or electrostatically
engineered BiFeO$_3$.

17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph