### Abstract

A quantum chemical method is proposed for the conformational analysis of very large biomolecules. The total wave function is constructed of localized bond fragments each determined on the basis of chemical intuition and model calculations on small molecules. The transferability of bond orbitals, localized strictly onto a few atoms of the molecule is discussed. The Löwdin procedure is applied to obtain orthogonalized molecular orbitals. The energy expression is calculated using the ZDO assumption. Simplified formulas for the Coulombic-type electronic interaction integrals are introduced. This approximation is similar to the assumption of the CNDO-method made in order to maintain rotational invariance. To obtain an energy expression, containing a number of terms proportional to N^{2}, (N is the number of occupied orbitals) the overlap of non-adjacent bond orbitals is neglected. At last a simple point-charge interaction is assumed to act between atoms lying far from each other. Thus the calculation of the energy involves the evaluation of a number of integrals proportional to the first power of N. Numerical results for H_{2}, Li_{2} and LiH are given.

Original language | English |
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Pages (from-to) | 261-273 |

Number of pages | 13 |

Journal | Acta Physica Academiae Scientiarum Hungaricae |

Volume | 40 |

Issue number | 4 |

DOIs | |

Publication status | Published - Apr 1976 |

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### ASJC Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

**Towards a molecular orbital method for the conformational analysis of very large biomolecules.** / Náray-Szabó, G.

Research output: Contribution to journal › Article

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TY - JOUR

T1 - Towards a molecular orbital method for the conformational analysis of very large biomolecules

AU - Náray-Szabó, G.

PY - 1976/4

Y1 - 1976/4

N2 - A quantum chemical method is proposed for the conformational analysis of very large biomolecules. The total wave function is constructed of localized bond fragments each determined on the basis of chemical intuition and model calculations on small molecules. The transferability of bond orbitals, localized strictly onto a few atoms of the molecule is discussed. The Löwdin procedure is applied to obtain orthogonalized molecular orbitals. The energy expression is calculated using the ZDO assumption. Simplified formulas for the Coulombic-type electronic interaction integrals are introduced. This approximation is similar to the assumption of the CNDO-method made in order to maintain rotational invariance. To obtain an energy expression, containing a number of terms proportional to N2, (N is the number of occupied orbitals) the overlap of non-adjacent bond orbitals is neglected. At last a simple point-charge interaction is assumed to act between atoms lying far from each other. Thus the calculation of the energy involves the evaluation of a number of integrals proportional to the first power of N. Numerical results for H2, Li2 and LiH are given.

AB - A quantum chemical method is proposed for the conformational analysis of very large biomolecules. The total wave function is constructed of localized bond fragments each determined on the basis of chemical intuition and model calculations on small molecules. The transferability of bond orbitals, localized strictly onto a few atoms of the molecule is discussed. The Löwdin procedure is applied to obtain orthogonalized molecular orbitals. The energy expression is calculated using the ZDO assumption. Simplified formulas for the Coulombic-type electronic interaction integrals are introduced. This approximation is similar to the assumption of the CNDO-method made in order to maintain rotational invariance. To obtain an energy expression, containing a number of terms proportional to N2, (N is the number of occupied orbitals) the overlap of non-adjacent bond orbitals is neglected. At last a simple point-charge interaction is assumed to act between atoms lying far from each other. Thus the calculation of the energy involves the evaluation of a number of integrals proportional to the first power of N. Numerical results for H2, Li2 and LiH are given.

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U2 - 10.1007/BF03157503

DO - 10.1007/BF03157503

M3 - Article

AN - SCOPUS:0000858823

VL - 40

SP - 261

EP - 273

JO - Acta Physica Academiae Scientiarum Hungaricae

JF - Acta Physica Academiae Scientiarum Hungaricae

SN - 0001-6705

IS - 4

ER -