Structural properties of crystalline uranium from linear combination of Gaussian-type orbitals calculations

Scalar-relativistic linear combinations of Gaussian-type orbitals-fitting f unction (LCGTO-FF) calculations, using the local density approximation (LDA ) and generalized gradient approximation (GGA) to density functional theory , were used to determine the atomic volumes, bulk moduli, and relative stab ilities of uranium in the fee, bcc, and alpha-U (orthorhombic) phases. The alpha-U phase is found to be the most stable, in agreement with experiment. The LDA yields an atomic volume that is about 7% smaller than experiment, while the GGA produces near perfect agreement with experiment. The numerica l stability of the LCGTO-FF results is tested by comparison with a similar series of scalar-relativistic calculations using the full-potential lineari zed augmented plane-wave (FLAPW) method. The results obtained with the two methods are in excellent agreement, demonstrating the ability of the LCGTO- FF method to address the properties of a light actinide metal in its low-sy mmetry alpha phase. (C) 1999 John Wiley & Sons, Inc.