MGGA formulation

[Dhirendra]

In the original paper from Tran and Blaha, they use sqrt(5/12) factor. But QuantumWise is using sqrt(4/12) factor in their formulation http://docs.quantumwise.com/tutorials/inas_2d_mgga/inas_2d_mgga.html.
Which is the implemented version?

[Petr Khomyakov]

This is a typo in the tutorial. Thanks for spotting it. But it is implemented correctly in the ATK code, where the factor of sqrt(5/12) was used in the formula for the MGGA-TB09 exchange potential, in consistency with the original work by Tran and Blaha.