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Fix cusp for NaN's and catch bracketing failures #1594

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merged 4 commits into from May 13, 2019

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@markdewing
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commented May 10, 2019

Three changes to address issues seen in #1542

  1. Increase the bracketing iteration count to 100,000 and add another step size increase at 10,000
  2. Catch the std::runtime exception thrown if the bracketing reaches the maximum iteration count, and abort the code with a better message. Unhandled exceptions are not reported well, especially under MPI.
  3. Add a small offset to the wavefunction correction in the effective local energy calculation to prevent division by zero.

markdewing added some commits May 10, 2019

Catch bracket errors during cusp minimization
The code to bracket a minimum throws an exception, which is not well
reported, espcially under MPI.  This catches the exception and aborts
the execution with a more visible message.

The effective local energy divides by the value of wavefunction correction.
If it is zero, the result is a NaN, which makes bracketing and minimization
run poorly.  This is a simple hack to prevent the denominator from being zero.

@ghost ghost assigned markdewing May 10, 2019

@ghost ghost added the in progress label May 10, 2019

@prckent
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We might compute some "real world" statistics on the amount of bracketing required. Presumably there are efficiencies to be had.

@ghost ghost assigned prckent May 13, 2019

@prckent prckent merged commit 1fb3b7b into QMCPACK:develop May 13, 2019

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@ghost ghost removed the in progress label May 13, 2019

@markdewing markdewing deleted the markdewing:cusp_nan_fix branch Aug 19, 2019

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