[Wien] IRelast error in C_ana_elast_lapw

[reyhaneh ebrahimi]

I think your error is due to the results of  (c11+2c12) = -0.091 (GPa)
(also the value of  c12 = -58.679 (GPa))  for order of fit=4. Because this
value does not satisfy  the  Born stability criteria.  In other words this
value should be positive to have the compound with mechanical stability.
However, to solve this, I suggest you at first check your input files
carefully and then change your volume% (or add other volumes% to your
current volumes%) that you select  for your current elastic calculations.
The best,
Reyhaneh Ebrahimi

On Thu, Sep 8, 2022 at 8:33 AM AJAY SINGH VERMA <ajay_phy at hotmail.com>
wrote:

> Dear all,
>
> While running C_ana_elast_lapw for my compound, I am getting following
> error given below in order of fit 4. Result for order 2 and 3 is being
> shown properly. Output order file has been attached.
> Kindly help.
>
>
> ORDER OF FIT IS :  4 , At volume = 2365.41197 (bohr^3) ########
> (c11-c12) = 175.946 (GPa)
> (c11+2c12) = -0.091 (GPa)
> (c44) = 1.175 (GPa)
> ________________________________________
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> (standard_in) 1: syntax error
> c11 = 117.267 (GPa)
> c12 = -58.679 (GPa)
> c44 = 1.175 (GPa)
> =======================================================================
>
> Prediction VOIGT Bulk modulus by using elastic constant values  = -.030
> (GPa)
> Prediction REUSS Bulk modulus by using elastic constant values  =  (GPa)
> Prediction HILL  Bulk modulus by using elastic constant values  =  (GPa)
>
> Prediction VOIGT Shear modulus by using elastic constant values = 35.894
> (GPa)
> Prediction REUSS Shear modulus by using elastic constant values =  (GPa)
> Prediction HILL  Shear modulus by using elastic constant values =  (GPa)
>
> Prediction VOIGT Young modulus by using elastic constant values = -.270
> (GPa)
> Prediction REUSS Young modulus by using elastic constant values =  (GPa)
> Prediction HILL  Young modulus by using elastic constant values =  (GPa)
>
> Prediction VOIGT Poisson's coefficient by using elastic constant values =
> -1.003
> Prediction REUSS Poisson's coefficient by using elastic constant values =
> Prediction HILL  Poisson's coefficient by using elastic constant values =
>
> You can find these data in the output-order file.
>
>
> Thanks and Regards.
>
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