How do I calculate Entrophy from kcalmol or from value given

How do I calculate Entrophy from kcal/mol? or from value given 643.2979au

Explain in steps

Solution

unit convertion:

    1 a.u = 1 hartree

             = 1 hartree [(627.51 kCal/mol)/(1 hartree)]

             = 627.51 kcal/mol

thus, the entholphy is,

     dH = 643.2979 au

           = 643.2979 au [( 627.51 kcal/mol) / au]

           = 403675.865229 kcal/mol

           = 4.0367e+5 kcal/mol