The fully two-dimensional Peierls barrier map of screw dislocations in body-centered cubic (bcc) iron has been calculated using the first principles method to identify the migration path of a dislocation core. An efficient method to correct the effect of the finite size cell used in the first-principles method on the energy of a lattice defect was devised to determine the accurate barrier profile. We find that the migration path is close to a straight line that is confined in a {110} plane and the Peierls barrier profile is single humped. This result clarifies why the existing empirical potentials of bcc iron fail to predict the correct mobility path. A line tension model incorporating these first-principles calculation results is used to predict the kink activation energy to be 0.73 eV in agreement with experiment.

No abstract

No abstract

With the help of the improved Monte Carlo renormalization-group scheme, we numerically investigate the renormalization group flow of the antiferromagnetic Heisenberg and XY spin model on the stacked triangular lattice (STA-model) and its effective Hamiltonian, 2N -component chiral φ 4 model which is used in the field-theoretical studies. We find that the XY-STA model with lattice size 126 × 144 × 126 exhibits clear first-order behavior. We also find that the renormalization-group flow of the STA model is well reproduced by the chiral φ 4 model, and that there are no chiral fixed points of renormalization-group flow for N = 2 and 3 cases. This result indicates that the Heisenberg-STA model also undergoes first-order transition.

The interpolating function between the Biersack and Ziegler universal screened-Coulomb form and the cubic spline fit was mistyped in Eq. ͑2͒ in the original paper as an exponential rather than a polynomial. The correct Fe-H two-body function should readwhere Z Fe and Z H are the atomic numbers of Fe and H, respectively; q e is the electronic charge; H͑ · ͒ is the Heaviside step function; r s = 0.88534a 0 / ͱ ͑Z Fe 2/3 + Z H 2/3 ͒ is the screening length, a 0 being the Bohr radius; andis the screening function. The square-root in the screening length was inadvertently omitted in the original paper. The knot point r 4 HFe in Table VIII in the original paper should be at 3.0 Å. Finally, the parameters for the interpolating polynomial should be revised as indicated in Table I; all other parameters remain unaltered. 1 Please note that these corrections only alter the Fe-H two-body interaction for distances below 1.2 Å, a range that is never actually sampled in any of the atomic configurations used in the fitting procedure. The Fe-H two-body interaction in all our configurations is completely described by the cubic splines-the interpolating polynomial and the Biersack-Ziegler form merely provide continuity below 1.2 Å. Hence, our results and conclusions remain unaltered.We are grateful to L. Proville and R. Matsumoto for bringing these errors to our attention. *ashwin@engin.umass.edu † itakura.mitsuhiro@jaea.go.jp ‡ eac@princeton.edu 1 Updated potential files formatted for use with LAMMPS may be downloaded from