Semi-empirical calculation of solid surface tensions in body-centred cubic transition metals

We present calculations of surface tension (surface stress γ)for the body-centred cubic (b.c.c.) metals V, Nb, Ta, Mo and W made using simple empirical N-body potentials obtained by Finnis and Sinclair (1984). Results for several crystal faces are evaluated and compared with the corresponding surface energies σ. Although there is a broad correlation between the calculated tensions and energies for different metals, and the two quantities are of a similar order of magnitude, they differ from one another by a factor of up to 2. Variant potentials for molybdenum were constructed to test the sensitivity of the results; negative surface tensions were found in some cases and shown to be a symptom of metastability of the b.c.c. structure.