  The present paper reports sim-trhepd-rheed (STR), an open-source simulator of
total-reflection high-energy positron diffraction (TRHEPD) and reflection
high-energy electron diffraction (RHEED) experiments which are used for
atom-scale surface structure determination of a material. The STR simulator is
used for the analysis of experimental diffraction data by simulating the
rocking curve from a given trial surface structure by solving the partial
differential equation of the dynamical quantum diffraction theory for positron
or electron wavefunctions. Using the obtained surface structure, electronic
structure, and other physical quantities can be evaluated through
first-principles calculations. For this purpose, a utility software was also
developed in order to realize a first principles calculation with the Quantum
ESPRESSO suite.
