A Formula of Non-Linear Responses

Abstract

Kubo's successive formula 1 l for non~linear irreversible properties needs an investigation of higher order correlations and a summing up of them. Whether this twostep approach can cover the essential natures of non-linear irreversible mechanism or not, seems to require further investigation. In this report, a quantum statisticalmechanical expression for the expectation value of a physical quantity in a disturbed