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Manuscript Title: Efficient kinematical simulation of reflection high-energy electron diffraction streak patterns for crystal surfaces
Authors: Kangkang Wang, Arthur R. Smith
Program title: RHEEDsim
Catalogue identifier: AEJC_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 182(2011)2208
Programming language: Matlab (version > 7.6.0).
Computer: Personal Computers.
Operating system: Windows with Matlab environment.
RAM: Greater than 1 MB
Keywords: Reflection high-energy electron diffraction (RHEED), kinematic, electron diffraction, surface reconstruction, computer simulations.
Classification: 7.4.

Nature of problem:
Reflection high-energy electron diffraction (RHEED) has been widely used in studying crystal surface structures all over the world, especially in combination with ultra-high vacuum molecular beam epitaxy systems. In addition to determining the surface smoothness, RHEED is also a very useful tool in studying surface reconstructions, which are often encountered at the growth surfaces of semiconductors and alloys. While the positions of the fractional streaks can be used to determine the basic information of the surface supercells, the intensity modulations on the fractional streaks provide further insights on the details within these unit cells. Kinematic approach is an efficient method for simulating the RHEED patterns based on various surface structural models, which can help unraveling the surface atomic structure.

Solution method:
The kinematic approach utilized here assumes single scattering events. Furthermore, the Ewald sphere is approximated into a planar surface for computing the streak intensities (which are most relevant to real experiments). Structure factors are calculated based on a given input of atomic species and their coordinates, with user modifiable form factors. In addition to the intensity modulation within the surface plane, addition modulations extending into the z direction is also taken into consideration, resulting in realistic density maps of the RHEED streaks, which can be directly compared to experimental observations.

Unusual features:
The main program RHEEDsim.m calls several local subprograms for certain computational tasks. As a result, all programs should be extracted into a single folder, and that folder should be set as the main directory in Matlab.

Running time:
The computing time is computer and user parameter dependent, but typically ranges from few seconds to few minutes.