Hartree-Fock crystal orbital

In addition, ab initio Hartree-Fock crystal orbital calculations were performed upon 5,7-dimethylaminothieno[3,4-d]pyrimidine (90MI8). 

Suhai S, Bagus PS, Ladik J (1982) An error analysis for Hartree-Fock crystal orbital calculations. Chem Phys 68 467 171... 

The formalism to incorporate translational symmetry into the usual Hartree-Fock approach, the crystal orbital technique, is not new at all 74,75). Reviews of recent devel-opements and applications of the Hartree-Fock crystal orbital method may be found in refs. 76 79). However, only few investigations on the evaluation of equilibrium geometries and other properties derived from computed potential surfaces of one-dimensional infinite crystals or polymers have been reported. 

In Section 2 we briefly summarize the basic mathematical expressions of the LCAO Hartree-Fock crystal orbital method both in its closed-shell and DODS (different orbitals for different spin) forms and describe the difficulties encountered in evaluating lattice sums in configuration space. Various possibilities for calculating optimally localised Wannier functions are also presented. They can be efficiently used in the calculation of excited states and correlation effects discussed in Section 3. 

Kertesz, M. Koller, J. Azman, A. Ab initio Hartree-Fock crystal orbital studies. J. Chem. Phys. 1978, 68, 2779-2782. 

In zeroth-order e is chosen to be diagonal and the result is the ordinary field-free Hartree-Fock crystal orbital equation. As usual C(k) is complex for arbitrary k. Apart from this aspect the most important difference between tlie crystal orbital and molecular TDHF perturbation equations is the presence of tlie dC/dk term in the former. Since dC/dk is multiplied by E, field-free derivatives of C(k) with respect to k appear for the first time in the first-order perturbation equations. These field-free... 

The electronic structures of poiy(fluoroacetylene) and poly(difluoroacetylene) have been investigated previously using the ab initio Hartree-Fock crystal orbital method with a minimum basis set (42). Only the cis and trans isomers with assumed, planar geometries were studied. The trans isomer was calculated to be more stable in both cases, and the trans compounds were predicted to be better intrinsic semiconductors and more conductive upon reductive doping than trans polyacetylene. However, our results show that head-to-tail poly(fluoroacetylene) prefers the cis structure and that the trans structure for poly(difluoroacetylene) will not be stable. Thus the conclusions reached previously need to be re-evaluated based on our new structural information. Furthermore, as noted above, addition of electrons to these polymers may lead to structural deformations that could significantly change the conductive nature of the materials. 

The self-consistent-field (SCF) ab initio Hartree-Fock crystal orbital method is applied with success to polysulfur nitride (SN)X, chains using non-local exchange and evaluating all integrals over atomic orbitals within 5 atomic neighbours accurately. 

We have applied the a. i. Hartree-Fock crystal orbital method to three nuclear configurations I was an equidistant chain with rg =1.62 K and all bond angles taken as 115° II was a chain taken from Boudelle s structure (4) chain III corresponded to the "Penn" structure (5). 

Bakhshi and coworkers [19-22] then reported studies of the electronic structures of polymers 8-21 in which the ah initio Hartree-Fock crystal orbital method was applied to optimized unit cell geometries obtained from the MNDO—AMI method. It was pointed out that this method largely overestimated all... 

These results were in agreement with a previous calculation done using an ab initio Hartree-Fock crystal orbital method with a 7s/3p minimal basis set with the zW-trans geometry taken from the Extended Huckel calculation [12]. This method allowed complete... 

Kertesz, M., J.Koller and A.Azman. Ab Initio Hartree Fock Crystal Orbital Studies II. Energy Bands of an Infinite Carbon Chain, J.Chem.Phys. 68 (1978) 2779-2782. 

Suhai, S. Ab Initio Hartree Fock Crystal Orbital Calculations on Polydiacetylene Backbones, Chem.Phys. 54 (1980) 91-101. 

Only Bredas et al. [1051, 1053] reported the results of calculations on the 5,6-dimethyl-, 5,6-dimethojqr-, and 5,6-dicyano-substituted aromatic polyisothianaphthene derivatives. From these data, it can be concluded that the overall effect of electron-donating and electron-withdrawing substituents is rather small and the reported bandgap values only show a difference of at most 0.05 eV. The results of ab initio Hartree-Fock crystal orbital calculations [1091] for dihydroxy- and dicyano-substituted poly(isonaphthothiophene) point in the same direction. 

Hartree-Fock Crystal-Orbital Theory of Periodic Polymers... 

Owing to the central role of DNA in biochemistry and biophysics, the computation of the electronic structure of periodic polymers constructed from nucleotide bases, base pairs, and nucleotides by applying the ab initio Hartree-Fock crystal-orbital method has attracted much... 

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