Structural stability of higher-energy phases and its relation to the atomic configurations of extended defects: The example of Cu

The total-energy calculations using a full-potential first-principles method have been performed for three displacive phase transformation modes in Cu. The structural and elastic properties of the ground-state (fcc) and higher-energy phases (bcc and $9R)$, as well as the energy barrier for sliding of $\{111{\}}_{\mathrm{fcc}}$ close-packed atomic planes and the stacking fault energy were obtained. Stability of higher-energy phases in the region of extended defects is discussed in detail. Examples presented are bcc and $9R$ Cu in grain boundaries and bcc Cu in pseudomorphic films at low temperatures. It is shown that the higher-energy phases, which are usually unstable, can be stabilized in the region of extended defects by certain imposed constraints.