Year: 2024
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Automatic differentiation (AD) offers a route to achieve arbitrary-order derivatives of challenging wave function methods without the use of analytic gradients or response theory. Currently, AD has been predominantly used in methods where first- and/or second-order derivatives are available, but it has not been applied to methods lacking available derivatives. The most robust approximation of explicitly correlated MP2, MP2-F12/3C(FIX)+CABS, is one such method. By comparing the results of MP2-F12 computed with AD versus finite-differences, it is shown that (a) optimized geometries match to about 10 –3 Å for bond lengths and a 10 –6 degree for angles, and (b) dipole moments match to about 10 –6 D. Hessians were observed to have poorer agreement with numerical results (10 –5 ), which is attributed to deficiencies in AD implementations currently. However, it is notable that vibrational frequencies match within 10 –2 cm –1 . The use of AD also allowed the prediction of MP2-F12/3C(FIX)+CABS IR intensities for the first time.
Institution: University of Georgia
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Funder: Basic Energy Sciences
Award: G411007485
OpenAlex ID: W4402731994