Joan van der Waals

Joan Henri van der Waals (2 May 1920 – 21 June 2022) was a Dutch physicist. He was professor of experimental physics at Leiden University between 1967 and 1989. He specialized in molecular physics and clathrate hydrates. One of Van der Waals's most significant contributions to the study of hydrates was a series of papers between 1953 and 1958, which eventually culminated in the 1959 publication of his paper on the canonical partition function for clathrates, along with J. C. Platteeuw. To create this partition function, van der Waals made a number of simplifying assumptions, most prominently that neighboring guest gas molecules cannot interact and there is a maximum of one guest per cage.