[Wien] Enthalpy of formation of K2UCl5

[Ghosh SUDDHASATTWA]

Dear Wien2k users, 

I was working on K2UCl5 compound with space group 62. It has 32 atoms per
primitive cell and is orthorhombic. I used the initso option for U. The
enthalpy of formation is given by 

Enthalpy =ENE(K2UCl5)-(2/8)ENE(K)-(1/8)ENE(U)-(5/8)ENE(Cl)

Or, 

Enthalpy =ENE(K2UCl5, with so)-(2/8)ENE(K)-(1/8)ENE(U,with
so))-(5/16)ENE(Cl2)

Since , the total energy of Cl2 cannot be directly implemented, I used the
following 

Exp_Enthalpy of KCl=ENE(KCl)-(1/2)ENE(K)-(1/4)ENE(Cl2)

Since the Exp_enthalpy of KCl is known, ENE(Cl2) was extracted. 

Rk_max was chosen as 8.00 for all ENE calculations with 1248 k-points for
K2UCl5. A smooth variation of energy vs c/a was obtained. 

The enthalpy of formation was found to be -472.3 kJ/mol which essentially
should be around -1200 kJ/mol seeing the trend in isostructural compounds. 

Can anybody suggest as to what the problem is? 

 

Is their any problem with the approach? 

 

Suddhasattwa 

 

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