Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Directional Phonon Suppression Function as a Tool for the Identification
  of Ultralow Thermal Conductivity Materials   Boundary-engineering in nanostructures has the potential to dramatically
impact the development of materials for high-efficiency conversion of thermal
energy directly into electricity. In particular, nanostructuring of
semiconductors can lead to strong suppression of heat transport with little
degradation of electrical conductivity. Although this combination of material
properties is promising for thermoelectric materials, it remains largely
unexplored. In this work, we introduce a novel concept, the directional phonon
suppression function, to unravel boundary-dominated heat transport in
unprecedented detail. Using a combination of density functional theory and the
Boltzmann transport equation, we compute this quantity for nanoporous silicon
materials. We first compute the thermal conductivity for the case with aligned
circular pores, confirming a significant thermal transport degradation with
respect to the bulk. Then, by analyzing the information on the directionality
of phonon suppression in this system, we identify a new structure of
rectangular pores with the same porosity that enables a four-fold decrease in
thermal transport with respect to the circular pores. Our results illustrate
the utility of the directional phonon suppression function, enabling new
avenues for systematic thermal conductivity minimization and potentially
accelerating the engineering of next-generation thermoelectric devices.

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The categories of this paper are: stat
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc