  To obtain a local description from highly accurate density functional theory
codes that are based on modified plane wave bases, a transformation to a local
orthonormal Wannier function basis is required. In order to do so while
enforcing the constraints of the space group symmetry the Symmetry Conserving
Maximally Projected Wannier Functions (SCMPWF) approach has been implemented in
the Full-Potential-Local-Orbital code, FPLO. SCMPWFs represent the zeroth order
approximation to maximally localized Wannier functions, projecting a subset of
wave functions onto a set of suitably chosen local trial-functions with
subsequent orthonormalization. The particular nature of the local orbitals in
FPLO make them an ideal set of projectors, since they are constructed to be a
chemical basis. While in many cases projection onto the FPLO basis orbitals is
sufficient, the option is there to choose particular local linear combinations
as projectors, in order to treat cases of bond centered Wannier functions. This
choice turns out to lead to highly localized Wannier functions, which obey the
space group symmetry of the crystal by construction. Furthermore we discuss the
interplay of the Berry connection and position operator and especially its
possible approximation, symmetries and the optimal choice of Bloch sum phase
gauge in cases where the basis is not explicitly known. We also introduce
various features which are accessible via the FPLO implementation of SCMPWFs,
discuss and compare performance and provide example applications.
