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.

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.