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6.6 Auxiliary Basis (Resolution of the Identity) MP2 Methods

6.6.9 Dual-Basis MP2

(July 14, 2022)

The successful computational cost speedups of the previous sections often leave the cost of the underlying SCF calculation dominant. The dual-basis method provides a means of accelerating the SCF by roughly an order of magnitude, with minimal associated error (see Section 4.7). This dual-basis reference energy may be combined with RI-MP2 calculations for both energies 1138 Steele R. P. et al.
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, 1137 Steele R. P., DiStasio, Jr. R. A., Head-Gordon M.
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and analytic first derivatives. 288 DiStasio, Jr. R. A., Steele R. P., Head-Gordon M.
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In the latter case, further savings (beyond the SCF alone) are demonstrated in the gradient due to the ability to solve the response (Z-vector) equations in the smaller basis set. Refer to Section 4.7 for details and job control options.