Comparisons of H2 calculated via several equivalent classes:
1500 K and 1 atm:
         NasaThermo   Nasa9   Nasa9_4reg 
  cp/R:      3.8823      3.8823      3.8823
  H/RT:     2.91015     2.91015     2.91015
  S/R:     21.5255     21.5255     21.5255
