The argument of the exponential should have have no dimension.

This bug was causing an infinite loop for thick slabs as the rcut was never converging.
43 jobs for hotfix_ewald_2D in 0 seconds
Status Job ID Name Coverage
  External
failed codecov/patch

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failed codecov/project

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passed distcheck

00:07:57

failed foss-2018a

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failed foss-2018a_debug

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failed foss-2018a_min

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failed foss-2018a_mpi

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failed foss-2018a_mpi_debug

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failed foss-2018a_mpi_min

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failed foss-2018a_mpi_opt

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failed foss-2018a_opt

00:48:07

failed foss-2018a_ppc

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failed foss-2018a_ppc_mpi

00:49:10

failed foss-2018a_valgrind

01:13:53

failed foss-2018b

00:48:04

failed foss-2018b_mpi

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failed foss-2019a

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failed foss-2019a_mpi

00:54:42

failed fosscuda-2018a

00:53:25

failed fosscuda-2018a_mpi

01:37:22

failed intel-2017a

00:51:05

failed intel-2017a_impi

00:53:58

failed intel-2017a_impi_omp

01:02:07

failed intel-2017a_omp

00:51:42

failed intel-2017b

00:49:33

failed intel-2017b_impi

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failed intel-2018a

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failed intel-2018a_impi

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failed intel-2018b

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failed intel-2018b_impi

00:50:03

failed intel-2019a

00:48:38

failed intel-2019a_impi

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failed pgi-2017.10

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failed pgi-2017.10_mpi

00:54:40

passed tests

02:30:56

failed codecov/patch

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failed codecov/project

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failed codecov/project

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failed codecov/project

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failed codecov/project

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