THEORY OF TEMPERATURE DEPENDENCE OF KNIGHT SHIFTS AND SPIN-LATTICE RELAXATION TIMES IN LIQUID LITHIUM AND SODIUM

Using a first-order pseudopotential perturbation procedure we have investigated the Knight shifts K and spin-lattice relaxation times T1 in liquid lithium and sodium both for their values at the melting points and the temperature dependences. The analysis uses temperature-dependent structure factors obtained from neutron - diffraction data. Our results for K and T1 at the melting point agree well with available data for both metals, the T1 data for lithium referring to 8Li nucleus being taken from polarized-neutron capture beta-decay technique and the other data from nuclear magnetic resonance measurements. For the temperature dependences, our calculations give positive slopes for K and (T1T)-1, a trend in agreement with experiment. However, while the slopes in sodium are in reasonable agreement with experiment with respect to magnitudes, they are substantially over-estimated for lithium. Arguments are presented for second-order effects of the pseudopotential in lithium as being the likely source for this difference between theory and experiment