Helium, neon and argon in copper studied with the effective medium theory

Two-component effective medium theory (EMT) is applied to calculate binding, migration and dissociation energies of helium, neon and argon in bulk copper. Interstitial helium and neon prefer octahedral sites whereas argon sits about 0.5 A off-centred in the octahedral site. Helium has the smallest migration energy, but, surprisingly, the migration energy of argon is smaller than that of neon. A vacancy in copper can bind three helium atoms or two neon atoms, but only one argon atom. Results are compared with those obtained from thermal desorption measurements.