Benchmark Investigation\nof SCC-DFTB Against Standard\nDFT to Model Phononic Properties in Two-Dimensional MOFs for Thermoelectric\nApplications

Despite the importance of modeling lattice thermal conductivity\nin predicting thermoelectric (TE) properties, computational data on\nheat transport, especially from first-principles, in 2D metal–organic\nframeworks (MOFs) remain limited due to the high computational cost.\nTo address this, we provide a benchmark of the performance of semiempirical\nself-consistent-charge density functional tight-binding (SCC-DFTB)\nmethods against density functional theory (DFT) for monolayer, serrated,\nAA-stacked and/or AB-stacked Zn<sub>3</sub>C<sub>6</sub>O<sub>6</sub>, Cd<sub>3</sub>C<sub>6</sub>O<sub>6</sub>, Zn-NH-MOF, and Ni<sub>3</sub>(HITP)<sub>2</sub> MOFs. Harmonic lattice dynamics calculations,\nincluding partial atomic contributions to phonon dispersions, are\nevaluated with both SCC-DFTB and DFT, whereas anharmonic transport\n(i.e., thermal conductivity) is evaluated with SCC-DFTB only. Our\nfindings further suggest that unlike the other stacking geometries\nmodeled, serrated Zn<sub>3</sub>C<sub>6</sub>O<sub>6</sub>, serrated\nZn-NH-MOF, and wavy serrated Ni<sub>3</sub>(HITP)<sub>2</sub> represent\nstable geometries. While Zn<sub>3</sub>C<sub>6</sub>O<sub>6</sub> and\nZn-NH-MOF exhibit a higher power factor than Ni<sub>3</sub>(HITP)<sub>2</sub> (as found in our previous work), Zn-NH-MOF shows lower thermal\nconductivity, resulting in the highest thermoelectric figure of merit\n(<i>ZT</i>) among the studied MOFs.