Correlation entropy and its relation to properties of liquid iron, cobalt and nickel

We present entropy calculations of liquid Fe, Co and Ni over an extended te mperature range of approximately 200 K above the melting point. The theory we use is based on a systematic expansion of the entropy in terms of the pa rtial N-particle distribution functions given first by Green for the canoni cal ensemble. First, we calculate the pair and triplet correlation entropie s using measured diffraction data. To evaluate the triplet correlation entr opy. we did not use the superposition approximation of Kirkwood in this wor k. Next, we calculate the self-diffusion coefficient based on Dzugutov's sc aling law using the pair and triplet correlation entropies. Then we estimat e the viscosity coefficient and the surface tension for these liquid metals using the Stokes-Einstein relation, the Born-Green equation and Fowler's f ormula for the surface tension. Predicted values of the self-diffusion coef ficient, the viscosity coefficient and the surface tension are reasonable i n comparison with available experimental data. (C) 2001 Elsevier Science B. V. All rights reserved.