AI Article Synopsis
- The text discusses a new method for calculating nuclear magnetic resonance (NMR) chemical shifts using an advanced theory called CP-CASSCF, which combines active space and perturbation techniques.
- It utilizes gauge-including atomic orbitals and optimized two-electron integrals to improve precision in calculations.
- Tests conducted on systems with up to 1300 basis functions show the method's efficiency and identify its computational limitations.
Article Abstract
We present an implementation of coupled-perturbed complete active space self-consistent field (CP-CASSCF) theory for the computation of nuclear magnetic resonance chemical shifts using gauge-including atomic orbitals and Cholesky decomposed two-electron integrals. The CP-CASSCF equations are solved using a direct algorithm where the magnetic Hessian matrix-vector product is expressed in terms of one-index transformed quantities. Numerical tests on systems with up to about 1300 basis functions provide information regarding both the computational efficiency and limitations of our implementation.
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