EN
The procedure suggested previously for the description of the square-well (SW) fluid within the framework of the mean spherical approximation is applied to calculate the structure factors of pure Na, pure K, and 0.5Na-0.5K alloy in liquid state. It is shown that our variations of the SW depth and SW width enable us to achieve a good agreement between calculated and experimental structure factors. The procedure under consideration gives more accurate results than the random phase approximation for the same values of the SW parameters.