Lowest-energy structures of odd-sized cationic P-2m+1(+) (m = 1-12) clusters have been determined from first-principles simulated annealing followed by more accurate geometry optimization within the framework of density functional theory. For P-n(+) with n > 11, the current global minimum structures are more favorable than those previously reported ones. A structural motif based on P-7, P-8, P-9, and P-10 building blocks and P-2 bridge was revealed for the medium-sized P-n(+) clusters. (C) 2009 Elsevier B. V. All rights reserved.