Description

Change the buffer to be from single precision to be double precision.

This increases the memory footprint but makes that the results remain identical when changing the parallelization. The result of the test finite_systems_3d/01-carbon become identical for non-MPI and MPI builders when we do this.

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.