𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Direct minimization of the Hartree—Fock expectation value of the hamiltonian

✍ Scribed by Jaroslav Koutecky´; Vlasta Bonacˇic´-Koutecky´

Publisher
Elsevier Science
Year
1972
Tongue
English
Weight
253 KB
Volume
15
Category
Article
ISSN
0009-2614

No coin nor oath required. For personal study only.

✦ Synopsis

The problem of direct minimization of the H-F energy expectation value is treated by introducing generalized eulerian angles in M dimensions. These are used to define Fermi spaces occupied by electrons with different spins. The common doubly occupied Fermi subspace can easily be determined in terms of these independent variables.

The method involves no constraints other than those explicitly introduced for convenience, such as the symmetry of the solution. The study of closed and open shell systems and diradieals is possible. Examples of singlet and triplet molecular states and doublet states of radicals in the PPP model are presented. Crossing of the singlet and triplet energies as function of molecular geometry is shown. The method is directly applicable also to all-valence semiempirical and ab-initio methods.

📜 SIMILAR VOLUMES

Restricted Hartree–Fock approximation. I
Restricted Hartree–Fock approximation. II. Computational aspects of the direct minimization procedure
✍ J. ÁNdez Fern Rico; M. Paniagua; J. I. ÁNdez Fern Alonso; P. Fantucci 📂 Article 📅 1983 🏛 John Wiley and Sons 🌐 English ⚖ 624 KB

## Abstract A RHF energy minimization procedure based on the treatment outlined in Part I of this series of articles is presented. Test calculations performed on several closed‐ and open‐shell systems show that the present procedure is definitely superior to the conventional SCF methods. In particu

Direct minimization of Hartree—Fock ener
Direct minimization of Hartree—Fock energy for alternant hydrocarbons in the PPP model
✍ J Koutecký; V Bonačić 📂 Article 📅 1971 🏛 Elsevier Science 🌐 English ⚖ 412 KB

The bond-order matrix &I the PPP model of alternant hydrocarbons is expressed in terms of.independe& parameters.and,.hence, the SCF energy itself is explicitly obtained in terms of these parameters. Direct minimization.of the ene&-y expression gives, besides those normally obtaikd, some new minima w