Quantum Electronic Stress: Density-Functional-Theory Formulation and Physical Manifestation

The concept of quantum electronic stress (QES) is introduced and formulated within density functional theory to elucidate extrinsic electronic effects on the stress state of solids and thin films in the absence of lattice strain. A formal expression of QES (sigma(QE)) is derived in relation to deformation potential of electronic states (Xi) and variation of electron density (Delta n), sigma(QE) = Xi Delta n as a quantum analog of classical Hooke's law. Two distinct QES manifestations are demonstrated quantitatively by density functional theory calculations: (1) in the form of bulk stress induced by charge carriers and (2) in the form of surface stress induced by quantum confinement. Implications of QES in some physical phenomena are discussed to underlie its importance.