This paper presents an alternative approach to designing multibend achromat (MBA) lattices with distributed sextupoles. It is based on the inherent structure of MBA lattices, which are composed of three smaller (recurring) substructures that can be optimized individually. These substructures consist of only a few elements; therefore, detailed parameter studies are feasible, and underlying principles can be revealed. The final linear lattice is a combination of the optimized substructures. Design decisions are mostly dictated by constraints, leaving limited alternatives under the given goals and boundary conditions. The linear lattice is constructed rather than optimized. Thus, it is justified to talk about a deterministic lattice design approach that provides a solid starting point for further fine-tuning and nonlinear optimization. The significance of time- and CPU-intensive optimization algorithms, such as multiobjective genetic algorithms, is much reduced. They can be used for fine-tuning the superperiod and for nonlinear optimization. Although the method optimizes the linear structure, it also considers nonlinear aspects such as chromatic sextupole strength and robustness against deviations from the design parameters. The approach was used to develop a lattice for the fourth-generation synchrotron light source BESSY III, planned at the Helmholtz-Zentrum Berlin. The design criteria and target values were taken from the BESSY III project. Different goals or boundary conditions may lead to alternative decisions or objectives to be considered. Implications of using this approach for higher energy or higher superperiodic lattices are briefly discussed. The resulting solution for BESSY III and initial nonlinear studies are presented.

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• Beam dynamics
• Beam optics
• Nonlinear beam dynamics
• Single-particle dynamics