Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ab initio computational study on the lattice thermal conductivity of
  Zintl clathrates [Si$_{19}$P$_{4}$]Cl$_{4}$ and Na$_{4}$[Al$_{4}$Si$_{19}$]   The lattice thermal conductivity of silicon clathrate framework Si$_{23}$ and
two Zintl clathrates, [Si$_{19}$P$_{4}$]Cl$_{4}$ and
Na$_{4}$[Al$_{4}$Si$_{19}$], is investigated by using an iterative solution of
the linearized Boltzmann transport equation (BTE) in conjuntion with ab initio
lattice dynamical techniques. At 300 K, the lattice thermal conductivities for
Si$_{23}$, [Si$_{19}$P$_{4}$]Cl$_{4}$, and Na$_{4}$[Al$_{4}$Si$_{19}$] were
found to be 43 W/(m K), 25 W/(m K), and 2 W/(m K), respectively. In the case of
Na$_{4}$[Al$_{4}$Si$_{19}$], the order-of-magnitude reduction in the lattice
thermal conductivity was found to be mostly due to relaxation times and group
velocities differing from Si$_{23}$ and [Si$_{19}$P$_{4}$]Cl$_{4}$. The
difference in the relaxation times and group velocities arises primarily due to
the phonon spectrum at low frequencies, resulting eventually from the
differences in the second-order interatomic force constants (IFCs). The
obtained third-order IFCs were rather similar for all materials considered
here.

32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
18
The categories of this paper are: econ