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HFALPHA

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HFALPHA = [real] 

Default: HFALPHA = 6/sqrt(ENMAX)/(2π) if HFRCUT is 0

Description: HFALPHA sets the decay constant used in the method of Massida, Posternak, and Baldereschi, which is activated by HFRCUT=0.


HFALPHA sets the decay constant in the error-function-like charge distribution for the method of Massida, Posternak, and Baldereschi[1]. The error-function-like charge distribution is used to calculate the difference between the isolated probe charge and the periodically repeated probe charge in a homogenous background. The default for HFALPHA is 6/sqrt(ENMAX)/(2π) in atomic units. This usually yields robust and accurate results in the range of meV compared to the Ewald summation used for a regular k-mesh. For more details, see HFRCUT=0.

Related Tags and Sections

HFRCUT