Exploring the Vibrational Behavior of Two-Dimensional Graphyne Allotropes for Millimeter-Wave Sensing and Autonomous Devices

In autonomous vehicle systems, millimeter-wave (mmWave) automotive radars are promising candidates for object detection. These systems include key components such as a signal-processing electronic circuit, a transmitter, and an mmWave receiver. The graphyne (GY) family ($\alpha$-,$\beta$-, and$\gamma$-GY) can represents a novel class of two-dimensional carbon allotropes that may serve as promising candidates for mmWave receivers; however, their attributes need to be evaluated for this application. In this regard, the present study aims to investigate the bending stiffness, stretching behavior, resonant frequencies, and mechanical stability of GY-based materials, as well as their interaction with mmWave in terms of their applicability as receiver materials. To achieve these goals, a hybrid approach combining continuum mechanics-based theory and molecular dynamics simulations is employed in addition to solving Maxwell's equations. The outcomes highlight the potential of GY sheets for object visualization within the frequency band of U (40-60 GHz), E (60-90 GHz), and D (110-170 GHz) for$\alpha$-GY; the F (90-140 GHz), V (50-75 GHz), and W (75-110 GHz) for$\beta$-GY; and the V (50-75 GHz), W (75-110 GHz), and Q (30-50 GHz) for$\gamma$-GY. An inverse relationship is observed between mmWave absorption and mechanical stability, with the absorption capability following$\alpha$-GY$>$$\beta$-GY$>$$\gamma$-GY. Moreover, with respect to vibrational modes, the order follows the same sequence as the absorption capability.