On the minimal energy of tetracyclic graphs
  The energy of a graph is defined as the sum of the absolute values of the eigenvalues of its adjacency matrix. In this paper, we characterize the tetracyclic graph of order $n$ with minimal energy. By this, the validity of a conjecture for the case $e=n+3$ proposed by Caporossi et al. \cite{CCGH} has been confirmed. 
Hongping Ma, Yongqiang Bai
math.CO