Organized by GPT-6-Astra. SPONGE 2.0 is under active, iterative development; features, parameters, and documentation may change. Consult the GitHub repository’s docs and skills for the latest version information.

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PME Electrostatics Parameters

PME is initialized through the PM module in the current source tree, so new TOML examples should prefer the [PM] scope:

[PM]
grid_spacing = 1.0
Direct_Tolerance = 1e-5
MPI_size = 1
print_detail = false

Some PME control keys are still read from the compatibility scope [PME]. This is a source-level behavior, not a separate algorithm.

[PM] Parameters

Parameter	Scope	Type	Default	Description
fftx	PM	int	auto	FFT grid size in X
ffty	PM	int	auto	FFT grid size in Y
fftz	PM	int	auto	FFT grid size in Z
grid_spacing	PM	float	1.0	Grid spacing in angstrom
Direct_Tolerance	PM	float	1e-5	Direct-space Ewald tolerance
MPI_size	PM	int	controller value	PME process count
print_detail	PM	bool	false	Print detailed PME energy breakdown

If fftx, ffty, and fftz are omitted, SPONGE derives them from grid_spacing and the current box dimensions.

MPI_size > 1 is currently rejected by the source code even if the key is present.

Compatibility Keys In [PME]

The following keys are read from the [PME] scope in the current source:

Parameter	Scope	Type	Default	Description
update_interval	PME	int	1	Reciprocal-space update interval
calculate_reciprocal_part	PME	bool	true	Whether to compute reciprocal-space PME
calculate_excluded_part	PME	bool	true	Whether to compute excluded-pair PME terms
replaced_by_PMC_IZ	PME	bool	false	Replace PME reciprocal evaluation with PMC-IZ

replaced_by_PMC_IZ = true cannot be used in npt mode.