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Internal Coordinates

Structure optimizations, see jobex, are most efficient if carried out in internal coordinates and TURBOMOLE offers the following choices.
based on bond distances and angles, see Section 4.1.2.
redundant internals

defined as linearly independent combinations of internals (see ref. [23]), provided automatically by the command ired in the `geometry main menu' in Section 4.1 below. This works in almost all cases and is efficient. The disadvantage is, that this is a black box procedure, the coordinates employed have no direct meaning and cannot be modified easily by the user.

should always work but are inefficient (more cycles needed for convergence). Cartesians are the last resort if other options fail, they are assigned as default if one leaves the main geometry menu and no other internals have been defined.