Forcefield params do not match between CPU and GPU #535
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The CPU and GPU can have different values for alpha^2. The reason is that the CPU apparently calculates a more accurate value of alpha^2 by using an intermediate value of alpha that is accurate to more than 64 bits, which it then squares.
To resolve this problem, the code has been changed to add new variables, gpu_alphaSq, gpu_rCutSq, and gpu_rCutCoulombSq, that are passed to the GPU, so the GPU uses the same values as the CPU for these variables. This also reduces the amount of computation, as we remove a multiplication each time we need the value of alpha^2.
The code is also updated to use the new alpha^2 value instead of recalculating it.
Unfortunately, the code also includes some reformatting of some files using clang-format, so the patch is larger than needed to resolve this issue.