In the processes studied in contemporary physics one encounters the most diverse conditions: temperatures ranging from absolute zero to those found in the cores of stars, and densities ranging from those of gases to densities tens of times larger than those of a solid body. Accordingly, the solution of many problems of modern physics requires an increasingly large volume of information about the propertiesofmatterundervariousconditions, includingextremeones. Atthesame time, there is a demand for an increasing accuracy of these data, due to the fact...