VDW_S9

VDW_S9 = [real]

Default: VDW_S9	= 1	if IVDW=13 (DFT-D4 package)
	= 0	if IVDW=15 (simple DFT-D3 package)
	= 0	if IVDW=11 or 12 (cannot be changed)

Description: VDW_S9 sets the contribution of the three-body term to the dispersion energy.

VDW_S9 allows to set the coefficient [math]\displaystyle{ s_{9} }[/math] that multiplies the three-body (Axilrod–Teller–Muto) term in the DFT-D3 and DFT-D4 methods implemented in the simple-DFT-D3 (IVDW=15) and DFT-D4 (IVDW=13) external packages, respectively.

Mind:

The VDW_S9 tag is available from VASP.6.6.0 onwards.
[math]\displaystyle{ s_{9}=0 }[/math] for IVDW=11 and 12 (VASP implementation of DFT-D3) and cannot be changed with VDW_S9.

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