  The Lie-Trotter formula $e^{\hat{A}+\hat{B}} = \lim_{N\to \infty}
(e^{\hat{A}/N} e^{\hat{B}/N})^N$ is of great utility in a variety of quantum
problems ranging from the theory of path integrals and Monte Carlo methods in
theoretical chemistry, to many-body and thermostatistical calculations. We
generalize it for the q-exponential function $e_q (x) = [1+ (1-q)
x]^{(1/(1-q))}$ (with $e_1(x)=e^x$), and prove $e_q(\hat{A}+\hat{B}+(1-q)
[\hat{A}\hat{B}+\hat{B}\hat{A}] /2) = \lim_{N\to \infty}
{[e_{1-(1-q)N}(\hat{A}/N)] [e_{1-(1-q)N}(\hat{B}/N)]}^N$. This extended formula
is expected to be similarly useful in the nonextensive situations

Statistical Mechanics