Thermodynamics of substances with negative thermal expansion and negative compressibility

Abstract It is shown that for substances with positive thermal expansion and positive compressibility, and for substances with negative thermal expansion and negative compressibility, δQ = d U + P d V , but for substances with positive thermal expansion and negative compressibility, and for substances with negative thermal expansion and positive compressibility, δQ = d U − P d V . The result obtained helps to calculate processes which do not obey traditional thermodynamics.