Relaxation and electronic surface states of rhodium surfaces

We present investigations of the structural and electronic properties of the low-index surfaces of rhodium based on selfconsistent ab initio local-density-functional calculations. Our technique is based on ultra-soft pseudopotentials, a preconditioned conjugate-gradient technique for the calculation of the electronic ground-state and of the Hellmann-Feynman forces, and a conjugate-gradient approach for the optimization of the atomic structure. For the (111), (100), and (110) surfaces inward relaxations of the top layer by -1.7 +/- 0.2, -3.8 +/- 0.2, and -9.8 +/- 0.6%, and an oscillatory decreasing relaxation of the deeper layers are predicted. A detailed analysis of electronic surface states is presented.