I am doing a simple thermodynamic analysis. Couldn't get thermodynamic values (such as internal energy, exergy, and so on) from common data base of CO2. I looked it up in REFPROP(By NIST) and EES. None of them have data below 212K. At one atmosphere CO2 sublime at about 195K. Could anyone explain this to me? How to calculate the internal energy and entropy when CO2 is in solid stae? Thank you very much!