QMCPACK / QMCPACK/qmcpack

Why is short-range potential LR_rc != Rws, the image radius?

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Description

`Uniform3DGridLayout::SetLRCutoffs` duplicates the functionality of `LatticeAnalyzer::calcSimulationCellRadius` and sets the short-range cutoff for the Coulomb potential to the simulation cell radius (Rsc). This is different from the default short-range cutoff radius of Jastrow and back flow functions set in `BsplineJastrowBuilder` and `BackflowBuilder`, respectively. The Bspline functor cutoff radius defaults to the image radius a.k.a. radius of the Cartesian space Wigner-Seitz cell (Rws).

For a non-orthorhombic cell, Rws>Rsc. My understanding is that Rws is the optimal cutoff radius for short-range functions. Therefore it bothers me to see the potential cutoff set to Rsc. Since the potential cutoff rc has no effect on the Ewald sum (so long as rc*kc is constant), is there any reason not to set rc=Rws? This would make potential and wavefunction consistent and help avoid confusion between Rsc and Rws.

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