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Re: Spin-free Exact Two-component Theory in Firefly

Wenli Zou


If nobody is developing X2C in Firefly, I'd like to do this interesting job.

In the past 4 years, my colleagues and I have developed the first and second derivatives of NESC (not the one in GAMESS and NWChem), which is closely related (or equivalent) to X2C. For example, see J. Chem. Theory Comput. 8, 2617 (2012).

After May 31 2015 I'll have a new position to develop relativistic methods. Howerver, to avoid legal problems, the new program has to be started from scratch. If my time is enough, the energy and gradient will be available at the end of 2015. Hope this is not too late.

Best regards,

On Mon Nov 17 '14 11:06am, ganymede wrote
>Hi Firefly Developers:

>Is there any plan or possibility to implement Spin-free exact two-component theory in its one-electron variant (SFX2C-1e) method, it offers accurate and efficient (essentially as efficient as the non-relativistic case) treatments of scalar-relativistic effects by a simple modification of the one-electron Hamiltonian matrix elements, and thus is highly recommended for scalar-relativistic calculations & also can count spin-orbit effects efficiently by perturbation.

>See Lan Cheng & Jürgen Gauss's recent published paper in JCP:

>Perturbative treatment of spin-orbit coupling within spin-free exact two-component theory:

>Spin-free Dirac-Coulomb calculations augmented with a perturbative treatment of spin-orbit effects at the Hartree-Fock level:

>Treatment of scalar-relativistic effects on nuclear magnetic shieldings using a spin-free exact-two-component approach:

>Analytic second derivatives for the spin-free exact two-component theory:

>Analytic energy gradients for the spin-free exact two-component theory using an exact block diagonalization for the one-electron Dirac Hamiltonian:

>Analytical evaluation of first-order electrical properties based on the spin-free Dirac-Coulomb Hamiltonian:

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