Spectral analysis and energy bounds for total zero-divisor graphs of the ring $\mathbb{Z}_{p^2q^2}$
This study investigates the spectral properties of the total zero-divisor graph associated with the ring $\mathbb{Z}_{p^2q^2}$, where $p$ and $q$ are distinct primes. Using an explicit equitable partition of the graph, we obtain a complete description of the adjacency spectrum. We show that the spectrum consists of two...