Precision of Electric-Field Gradient Predictions by Density Functional Theory and Implications for the Nuclear Quadrupole Moment and Its Error Bar of the 111 Cd 245 keV 5/2 + Level

ERRICO, LEONARDO; LEJAEGHERE, KURT; RUNCO, JORGE; MISHRA, S. N.; RENTERÍA, MARIO; COTTENIER, STEFAAN

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2016 vol. 120 p. 23111 - 23120

1932-7447

Wepresent ab initio calculated electric-field gradient tensors at Cd sites in aset of simple yet diverse noncubic metals. By combining these predictions withcarefully selected published experimental data, the nuclear quadrupole momentof the 245 keV 5/2+ level of 111Cd is determined to be0.76(2) b. Knowing this quadrupole moment is important for time-differentialperturbed angular correlation spectroscopy: decades of experimentally obtainednuclear quadrupole coupling constants for solids can now be more reliablyconverted into electronic structure information. For nuclear physicssystematics, this is a rare opportunity to have reliable quadrupole momentinformation for a short-lived level that is not accessible to regularexperimental methods. Much effort is spent on the determination of a meaningfulerror bar, which is an aspect that gained only recently more attention in thecontext of density functional theory predictions. This required assessing thenumerical uncertainty in density functional theory predictions forelectric-field gradient tensors in solids. In contrast to quantum chemistrymethods, these density functional theory predictions cannot detect systematicerrors. By comparing our quadrupole moment value with an independent valueobtained from quantum chemistry calculations and experiment, we show thatsystematic errors are small for the systems studied here. Yet, there areindications that density functional theory underestimates by a few percent theelectric-field gradient, and therefore overestimates the quadrupole moment bythe same amount. We point out which future work needs to be done tocharacterize the possible deviations inherent to density functional theory.