## Abstract

An analytical method was elaborated to compute the second derivative of the Hartree-Fock energy with respect to the unit cell length (Ỹ) in stereoregular polymers. The evaluation of Ỹ was performed in a single-shot calculation once the optimal geometry is known. The formulas necessary to calculate cell and mixed Hessians of individual one- and two-electron integrals were implemented efficiently. A seven-step CPHF procedure was used to obtain the derivatives of the density matrix in a fashion consistent with the SCF procedure. Using an adapted long-range effects scheme and efficient quadrature methods for transforming k-space density matrix and its derivatives into their real-space counterparts, an accuracy of 10^{-9} a.u. was obtained on the final Hessian elements.

Original language | English |
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Pages (from-to) | 373-388 |

Number of pages | 16 |

Journal | The journal of chemical physics |

Volume | 118 |

Issue number | 1 |

DOIs | |

Publication status | Published - 1 Jan 2003 |