... response¹

Throughout this document when referring to the first-order (or linear) response, we will simply use ``response'', for brevity.

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... eV²

The C_00 and H_00 norm-conserving pseudopotentials were used.

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... ARPACK³

http://www.caam.rice.edu/software/ARPACK/

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... Library)⁴

http://www.hsl.rl.ac.uk

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... CPMD⁵

http://www.cpmd.org

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... used.⁶

It is reasonably straightforward to extend Hutter's derivation to a single arbitrary k-point. The complex representation of the response density in equation 6 (above) allows for this extension. The equations for multiple k-points are not trivial and would require further research, and is therefore beyond the scope of this dCSE.

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... eigenvalues.⁷

While this should never happen in the case of pure functionals, negative eigenvalues are known to occur in TD Hartree-Fock theory. It is unclear whether they can occur in hybrid TDDFT.

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