Finite volume dependence of the quark-antiquark vacuum expectation value

A general formula is derived for the finite volume dependence of vacuum expectation values analogous to Lüscher's formula for the masses. The result involves no integrals over kinematic quantities and depends only on the matrix element between pions at zero momentum transfer thus presenting a new way to calculate the latter, i.e. pion sigma terms. The full order p6 correction to the vacuum condensate 〈q¯q〉 is evaluated and compared with the result from the Lüscher formula. Due to the size of the p6 result no conclusion about the accuracy of the Lüscher formula can be drawn.