Correlated self‐diffusion in a screw dislocation in a face‐centered‐cubic crystal is treated with a vacancy mechanism using matrix functions that are generated to permit the length of the dislocation to approach infinity for the tight‐binding approximation. The correlation factorffor positive vacancy binding to the dislocation is found to lie in the range 0.819≥f≥0.516. Previous calculations for a screw dislocation in a simple cubic structure are in the range 0.74≥f≥0.52, and are viewed as representing the differences associated with the core structure. Comparable calculations of the diffusion coefficient suggest that it becomes indefinitely large in the limit where the vacancies are tightly bound to the dislocation core but with a finite concentration in the surrounding lattice which is in agreement with similar limits for other dislocations.