The effect of four-phonon interaction on phonon thermal conductivity of hexagonal VTe₂ and puckered pentagonal VTe₂

The traditional view is that complex structures have lower lattice thermal conductivity. However, it is observed that complex structures have higher lattice thermal conductivity than simple atomic structures in VTe₂ systems after considering the four-phonon scattering effect. In this work, we calculate the lattice thermal conductivity of an H-VTe₂ monolayer with a simple atomic structure and that of a PP-VTe₂ monolayer with a complex atomic arrangement using first-principles calculations combined with the Boltzmann transport theory under the conditions of with and without the four-phonon scattering process. Our findings reveal that the lattice thermal conductivity of the PP-VTe₂ monolayer along the x or y direction is 3-4 times lower than that of the H-VTe₂ monolayer when only considering the three-phonon scattering process. After taking into account the four-phonon scattering process, the lattice thermal conductivity of both monolayers decreases. For the H-VTe₂ monolayer, the lattice thermal conductivity decreases by 88.7% (from 1.33 to 0.15 W m^-1 K^-1) compared to only considering the three-phonon scattering process, mainly due to strong four-phonon scattering. In addition, the PP-VTe₂ monolayer experiences a lower decrease in lattice thermal conductivity, with reductions of 12.5% (from 0.4 to 0.35 W m^-1 K^-1) and 11.7% (from 0.34 to 0.3 W m^-1 K^-1) in the x and y directions, respectively, because of the weak four-phonon scattering. Notably, the lattice thermal conductivity with the four-phonon scattering process of the H-VTe₂ monolayer is twice as low as that of the PP-VTe₂ monolayer. Hence, our findings suggest that even simple atomic structures can exhibit lower lattice thermal conductivity than complex structures when considering four-phonon interaction.