V knige predstavlen variatsionnyy printsip dlya termodinamicheskogo potentsiala, kotoromu podchinyayutsya chastichnye funktsii raspredeleniya ravnovesnoy statisticheskoy fiziki. Na osnove etogo printsipa mozhno poluchat' termodinamicheski soglasovannye priblizheniya vozrastayushchey tochnosti dlya chastichnykh funktsiy raspredeleniya. Rassmotreny takzhe primenenie etogo printsipa k issledovaniyu nekotorykh modeley, svoystv kriticheskoy tochki zhidkost'-gaz, k probleme poverkhnostnogo natyazheniya zhidkosti, probleme perekhoda zhidkost'-kristall. Predstavlen takzhe variatsionnyy printsip, kotoromu udovletvoryayut unarnaya i binarnaya matritsy plotnosti kvantovykh sistem, a takzhe obshchaya formulirovka variatsionnogo printsipa dlya matrits plotnosti proizvol'nogo poryadka. Kniga prednaznachena dlya studentov starshikh kursov, aspirantov i nauchnykh rabotnikov, zanimayushchikhsya problemami statisticheskoy fiziki i osobenno -- statisticheskoy teoriey zhidkostey.