I am writing this post to make anybody who might be using numerical orbitals in their QMC calculations aware of a bug we (myself and Neil Drummond) have found. If you have compiled CASINO on a version of gfortran >= 4.9, and are using numerical orbitals in DMC, there is a high chance that you have suffered an issue (in our test case, the DMC energy of Neon with a numerical basis, as found in CASINO/examples/atom/neon_n, was found to lie 4 a. u. lower than the current best estimate in a non-bugged version - which is consistent with earlier values reported in the literature). This is a problem that arises from a known point in the source code and it will be fixed in the near future.
A temporary workaround to this problem, which does not require installation of a new (or in this case old) gfortran version, is to make the following subsitution in the file "CASINO/arch/data/f90/gnu.arch" : the "-Ofast" flag should be replaced by -> "-O3 -ffast-math -fstack-arrays".
I.e. the line
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FFLAGS_opt = -Ofast -fpeel-loops -fcray-pointer
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FFLAGS_opt = -O3 -ffast-math -fstack-arrays -fpeel-loops -fcray-pointer
Regards,
Ryan.