Discussion about the precision: #300
For NaCl test cell (2 at) , D3Calculator (float32) gives -0.531394 eV,
while dftd3 fortran calculator and BatchD3 (float32 + kahan) gives -0.531417 eV.
Although the discrepancy (1e-5 eV/at order) are small, this discrepancy can be disappeared using kahan compensated summation method into 1e-8 eV/at order) with nearly zero additional cost.
The only one concern is backward compatibility.
Discussion about the precision: #300
For NaCl test cell (2 at) , D3Calculator (float32) gives -0.531394 eV,
while dftd3 fortran calculator and BatchD3 (float32 + kahan) gives -0.531417 eV.
Although the discrepancy (1e-5 eV/at order) are small, this discrepancy can be disappeared using kahan compensated summation method into 1e-8 eV/at order) with nearly zero additional cost.
The only one concern is backward compatibility.