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Calculation Of Diagonal Born-Oppenheimer Corrections

Corrections for making the Born-Oppenheimer approximations in the quantum chemical treatment of atoms and molecules are easily computed using perturbation theory. The lowest-order correction is obtained in first-order and takes the form

{$\Delta E_{DBOC} = \langle \Psi_{el} | \sum_A - \frac{\hbar^2}{2 M_A} \nabla_A^2 | \Psi_{el}\rangle $}

This correction is known as the diabatic Born-Oppenheimer correction (DBOC) and its inclusion leads to the so-called adiabatic approximation with mass-dependent potentials that are different for the various isotopologues of a molecule.

theoretical details to DBOC corrections

implementational details to DBOC corrections

The DBOC is calculated by simply invoking the keyword


Note that CFOUR calculates the DBOC using nuclear masses.

Note that DBOC can be computed at the HF-SCF, MP1, MP2 as well as the CCSD level for both RHF and UHF reference functions. ROHF may only be used at the HF-SCF level.

Note that geometry optimizations including DBOC can be carried out using numerically evaluated gradients via METHOD=ENERONLY.


calculation of DBOC

geometry optimizations including DBOC

calculation of DBOC using non-standard isotopomers

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Page last modified on January 10, 2013, at 05:00 PM
CFOUR is partially supported by the U.S. National Science Foundation.