Canonical entropy of higher-dimensional Reissner-Nordstroem Black hole

Recently, Hawking radiation of the black hole has been studied using the tunnel effect method. It is found the radiation spectrum of the black hole is not a strictly pure thermal spectrum. How the departure from pure thermal spectrum affects the entropy? This is a very interesting problem. In this paper, we calculate the partition function by energy spectrum obtained by tunnel effect. Using the relation between the partition function and entropy, we derive the expression of entropy the general charged black hole. In our calculation, we not only consider the connection to the black hole entropy due to fluctuation of energy but also consider the effect of the change of the black hole charges on entropy. We discuss higher-dimensional Reissner-Nordstroem black hole and obtain the relation among the lower limit of energy value, the charges and energy of the black hole. We derive that higher-dimensional Reissner-Nordstroem black hole cannot approach the extreme black hole by changing its charges. (authors)