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Geometry Optimizations

Geometry optimizations using analytic gradient techniques are possible for the following schemes:

• HF-SCF
• TCSCF
• MP2
• MP3
• MP4
• CC2
• CCD
• QCISD
• CCSD
• QCISD(T)
• CCSD(T)
• CCSDT-n (n=1-4)
• CC3
• CCSDT

Except for CC3, CCSDT-n, and CCSDT (closed-shell (RHF) only), geometry optimizations are possible for RHF, UHF, ROHF, and QRHF reference functions.

Geometry optimizations based on numerically evaluated gradients are possible for all methods available in CFOUR for energy calculations.

Geometry opimizations for all CI methods as well as for CC methods with triple and higher excitations (RHF, UHF, and ROHF reference functions) are possible via the MRCC code by M. Kállay which has been interfaced to CFOUR (see Interface to MRCC).

Optimization schemes are available to determine equilibrium geometries as well as transition states.