Abstract:

Shou Chin Wang (Wang Shoujing) was one of the few Chinese physicists who made significant contributions to the early development of quantum mechanics. One of his representative works is the study on the van der Waals potential based on quantum mechanics. Specifically, using the second-order perturbation theory in quantum mechanics, he derived a long-range attractive potential of the form −1/R⁶ between two widely separated atoms. Since individual atoms are non-polar, meaning their average dipole moments are zero, this interaction arises from fluctuations in the instantaneous electric dipole moments of the two atoms. 

Subsequently, Fritz London conducted a more systematic study of the interaction potential between non-polar molecules. In later literature and textbooks, this result is commonly referred to as the London dispersion force. London’s work indeed contains more extensive physical contents, but its core conclusion—the long-range behavior of the van der Waals potential—is consistent with Wang’s result. Wang’s work was published in Physikalische Zeitschrift, 28, 663 (1927), while London’s work appeared in Zeitschrift fur Physik, 60, 491 (1930). Wang’s publication was clearly earlier, and London cited Wang’s work. Hence, it would be appropriate to refer to this effect jointly as the “Wang-London force.” 

For quantum chemistry, Wang’s 1927 paper is one of the important early works in this direction. However, Wang’s research on the van der Waals attraction is not widely known in the academic community. For example, it was not included in the collection of classic papers, Quantum Chemistry—Classic Scientific Papers, edited by H. Hettema. 

The original German text of Wang’s article is not easy to find. I would like to thank my former student, Shenglong Xu (now an assistant professor at Texas A&M University), who helped me find an electronic version. I do not understand German and inquired with many people about an English translation of this article, but none could be found. The lack of an easily accessible English translation may be one reason why this work is not well-known.

To facilitate reading, I used Google Translate to translate Wang’s article into English. I also thank Professor Honghao Tu of Ludwig-Maximilians-Universit¨at M¨unchen, who proofread the translated draft and provided many valuable suggestions. During the translation and review process, some typographical errors in the original German text were identified and marked with translator’s and reviewer’s notes. 

On the centennial of the establishment of quantum mechanics, we believe it is meaningful to translate this classic paper by Shou Chin Wang into English.