Strictly localized molecular orbitals

Śurján, Péter R.; Révész, M.; Mayer, I.

doi:10.1039/f29817701129

Cited by 32 publications

(13 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One can use some standard completely transferrable set of values for the h i bond polarities, determined, e.g., by the electron negativities of the atoms between which the bond in question is formed [ l l , 201. It seems, however, it is more appropriate to determine the polarities fully variationally [12][13][14]211. This means that we solve the 2 x 2 HFR problem for each bond incorporating the influence of all other bonds on the given one into the effective core.…”

Section: Methodsmentioning

confidence: 99%

“…For example, qualitative reproduction of molecular electrostatic potentials is already possible by using completely transferable SLBOS [ll]. Net atomic charges, bond lengths, bond angles, and multipole moments can be calculated with sufficient accuracy, if inductive effects are also accounted for, but without departing from the strictly localized BOS [12][13][14]. Rotational barriers around single bonds, however, cannot be reproduced correctly if tails of orthogonal localized BOS are neglected.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Conformational analysis by bond orbitals with delocalization corrections: Rotation of the ser‐195 side chain in α‐chymotrypsin

Śurján

Náray‐Szabó

Mayer

1982

Int J of Quantum Chemistry

Self Cite

View full text Add to dashboard Cite

A recently developed procedure for calculation of tails of localized molecular orbitals is applied in order to obtain approximate rotational potential curves. In order to calculate reliable rotational barriers, tails, originating from direct interactions between bonding and antibonding strictly localized orthogonal orbitals, have to be determined. This finding permits us to develop a fast approximate SCF semiempirical procedure offering a reliable tool for studying conformational problems in rather large (bio)molecules. As a first example, a model of the active site of a-chymotrypsin was examined. According to our calculations, a hydrogen bond between Ser-195 and His-57 should exist.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Conformational analysis by bond orbitals with delocalization corrections: Rotation of the ser‐195 side chain in α‐chymotrypsin

Śurján

Náray‐Szabó

Mayer

1982

Int J of Quantum Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…In this way orbitals strictly localized on few atoms, namely, extremely localized molecular orbitals or ELMOs, are obtained. 31,32 Unfortunately, as already observed by several authors, [33][34][35][36][37][38][39][40][41][42][43][44] an important problem connected with the ELMO description is that the energy associated with the ELMO wavefunction is, not unexpectedly, higher than the corresponding Hartree-Fock one. 21 Moreover, through a series of preliminary studies we have shown the transferability of ELMOs, 20,[22][23][24][25]28 which has stimulated us to develop DENPOL, 26,28 a program that allows for the computation of ab initio quality electron densities for polypeptides through a database of suitable model compounds for all the aminoacids and a database of extremely localized molecular orbitals determined for these model molecules.…”

Section: Introductionmentioning

confidence: 95%

A Hylleraas functional based perturbative technique to relax the extremely localized molecular orbital wavefunction

Genoni¹,

Merz²,

Sironi³

2008

The Journal of Chemical Physics

View full text Add to dashboard Cite

A way to reduce the computational cost associated with the study of large molecules exploits the transfer of extremely localized molecular orbitals (ELMOs). Unfortunately, due to the reduction in the number of variational parameters, the ELMO description is not as accurate as the Hartree-Fock one, although it is qualitatively correct in most of the cases. Therefore, in order to overcome this significant drawback, we propose a perturbative ELMO approach exploiting the Hylleraas functional. Preliminary tests have been performed and the results are promising for future applications to large systems.

show abstract

“…For closed-shell classical molecules we define one-center lone pairs, two-center u-, and many-center a-orbitals [19][20][21][22][23] 4: For the subsystem we expand the wavefunction on the basis HYOS (2Ns is the number of electrons in the subsystem):…”

Section: Basis Setmentioning

confidence: 99%

The neglect of diatomic differential overlap (NDDO) fragment self-consistent field method for the treatment of very large covalent systems

Náaray-Szabó

Tóth

Ferenczy

et al. 1994

Int. J. Quantum Chem.

View full text Add to dashboard Cite

We present a semiempirical NDDO procedure, called the fragment SCF (FSCF) method, to treat very large molecules. The covalent system is partitioned into a relatively small subsystem where substantial chemical changes take place and an environment that remains more-or-less unperturbed during the process. We expand the wavefunction on an atomic hybrid basis and perform an SCF procedure for the subsystem in the field of the iteratively determined electronic distribution of the environment. We wrote a program for the IBM ~lSC/560 computer and did several test calculations for a variety of large classical molecules. Protonation energies, proton transfer potential curves, rotational barriers, atomic net charges, and HOMO and LUMO energies, as computed by the exact version of the NDDO method, are fairly well reproduced by our approximation. Using the FSCF method, we calculated the molecular electrostatic potential on the van der Waals envelopes of the specificity pocket of trypsin and the lysine side chain of the bound substrate and visualised electrostatic complementarity. We developed a novel bulk phase Monte Carlo simulation technique and calculated the energy by the above approximation and applied the method to amorphous silicon (a&). Starting from a distorted tetrahedrally bonded random network model of a-Si with 2 16 atoms, we performed Monte Carlo simulations using the FSCF energy calculation. For the second and subsequent configurations, we exploited the feature of the Metropolis-Teller algorithm, namely, that, to generate a new configuration, we displace only a single atom. Thus the number of integrals to be calculated drastically decreases since only those have to be reevaluated that contain the coordinates of the displaced atom. After equilibration we obtained distribution functions being almost identical to the one corresponding to the distortion free tetrahedrally bonded network. The same technique was applied to liquid chlorosilanes. We found that Si-CI bonds elongate by 6 to 16 pm while H-Si-CI and C1-Si-CI angles change by 2-4" as compared to the gas phase.

show abstract

Strictly localized molecular orbitals

Cited by 32 publications

References 0 publications

Conformational analysis by bond orbitals with delocalization corrections: Rotation of the ser‐195 side chain in α‐chymotrypsin

Conformational analysis by bond orbitals with delocalization corrections: Rotation of the ser‐195 side chain in α‐chymotrypsin

A Hylleraas functional based perturbative technique to relax the extremely localized molecular orbital wavefunction

The neglect of diatomic differential overlap (NDDO) fragment self-consistent field method for the treatment of very large covalent systems

Contact Info

Product

Resources

About