LOCALIZED MOLECULAR ORBITALS,

LOCAL CORRELATION METHODS

AND THEIR APPLICATIONS

A dissertation submitted in partial fulfillment

of the requirements for the degree of

Doctor of Philosophy

By

JAMES WHITE BOUGHTON, B.S., M.A.

University of Massachusetts, 1984

University of Texas, 1990

May 1994

University of Arkansas

This dissertation is approved for

recommendation to the

Graduate Council

Dissertation Director:

___________________________________

Peter Pulay

___________________________________

James Hinton

___________________________________

John Ewbank

___________________________________

William Harter

Dedicated to my father

Table of Contents

Introduction....................................................................................................................... 1

Chapter 1 - The Local Correlation Method...................................................................... 8

Rationale............................................................................................................... 8

Other Methods...................................................................................................... 10

Automatic virtual space selection............................................................................ 11

Chapter 2 - Comparison of Orthogonal Localizations....................................................... 16

Chapter 3 - Nonorthogonal Orbitals................................................................................. 24

Introduction........................................................................................................... 24

Method................................................................................................................. 25

MO-MO overlap Limitation................................................................................... 31

Discussion............................................................................................................. 34

Chapter 4 - Applications of the LC Method..................................................................... 49

Part 1 - The Tautomers of Uracil............................................................................ 49

Results and Discussion........................................................................................... 55

Conclusion to part 1.............................................................................................. 60

Part 2 - Three Conformers of N-acetyl -N’ -methyl glycyl amide........................... 60

Conclusion to part 2.............................................................................................. 62

Chapter 5 - 6-31G** Offset Forces................................................................................ 74

List of Tables

Table 2.1. - Characteristics of different localization schemes............................................... 18

Table 2.2 - Pipek Vs. Boys performance........................................................................ 22

Table 4.1 - 6-31G* Offset Forces................................................................................... 55

Table 4.2 - Hartree-Fock and Correlation Energies for Uracil Tautomers.......................... 56

Table 4.3 - Relative Energies of Uracil Tautomers (kJ/mol). .......................................... 58

Table 4.4 - Representative execution times for Uracil MP4............................................... 59

Table 4.5 - Glycyl dipeptide Conventional 6-31G** Geometries (Angstroms)................... 66

Table 4.6 - Glycyl dipeptide 6-31G**/Offset Forces Geometries (Angstroms)................ 67

Table 4.7 - Hartree-Fock and Correlation Energies for glycyl dipeptide conformers.......... 68

Table 4.8 - Relative energies of glycyl dipeptide conformers............................................. 69

Table 4.9 - Length of hydrogen bonding in glycyl dipeptide conformers............................. 70

Table 4.10 - Amide nonplanarity in glycyl dipeptide conformers I and III.......................... 70

Table 4.11 - Mulliken Charges for glycyl dipeptide........................................................... 71

Table 5.1 - 6-31G** Offset Force Functions................................................................... 75

Table 5.2 - 6-31G** Starting Offset Forces .................................................................... 76

Table 5.3 - Utility of Offset Forces - Uracil...................................................................... 77

Table 5.4 - Utility of Offset Forces - Glycyl dipeptide....................................................... 78

Table 5.5 - 6-31G** Offset Forces Dataset..................................................................... 92

List of Figures

Figure 1.1 - Inter-bond correlation energies of Alanine..................................................... 3

Figure 1.2 - Intra-bond correlation energies of Dimethyl Ether.......................................... 4

Figure 1.3 - Correlation energies of Diborane................................................................... 5

Figure 1.4 - Correlation energies of Oxirane..................................................................... 6

Figure 1.5 - Correlation energies of Dimethyl Ether........................................................... 7

Figure 3.1 - Ethanol LCAO coefficients less than 0.0001................................................. 37

Figure 3.2 - Ethanol LCAO coefficients less than 0.00001............................................... 38

Figure 3.3 - Ethanol LCAO coefficients less than 0.000001............................................. 39

Figure 3.4 - Alanine LCAO coefficients less than 0.0001................................................. 40

Figure 3.5 - Alanine LCAO coefficients less than 0.00001............................................... 41

Figure 3.6 - Alanine LCAO coefficients less than 0.000001............................................. 42

Figure 3.7 - Benzene LCAO coefficients less than 0.0001............................................... 43

Figure 3.8 - Benzene LCAO coefficients less than 0.00001............................................. 44

Figure 3.9 - Benzene LCAO coefficients less than 0.000001........................................... 45

Figure 3.10 - p-hydroxy benzoic acid dimer LCAO coefficients less than 0.0001................ 46

Figure 3.11 - p-hydroxy benzoic acid dimer LCAO coefficients less than 0.00001.............. 47

Figure 3.12 - p-hydroxy benzoic acid dimer LCAO coefficients less than 0.000001............ 48

Figure 4.1 - Geometry of Uracil Tautomers...................................................................... 51

Figure 4.2 - Geometry of Uracil Tautomers...................................................................... 52

Figure 4.3 - 6-31G* Offset forces used for Uracil............................................................ 54

Figure 4.4 - 6-31G* Offset forces used for Uracil............................................................ 54

Figure 4.5 - Conformer I (C7eq)...................................................................................... 63

Figure 4.6 - Conformer II (b)............................................................................................ 64

Figure 4.7 - Conformer III (b’)......................................................................................... 65

Figure 5.1 - C-C 6-31G** Offset Forces Fit.................................................................. 80

Figure 5.2 - C-N 6-31G** Offset Forces Fit.................................................................. 81

Figure 5.3 - C-O 6-31G** Offset Forces Fit.................................................................. 82

Figure 5.4 - C-H 6-31G** Offset Forces Fit................................................................... 83

Figure 5.5 - O-H 6-31G** Offset Forces Fit.................................................................. 84

Figure 5.6 - N-H 6-31G** Offset Forces Fit.................................................................. 85

Figure 5.7 - C-C 6-31G** Starting Offset Forces Fit...................................................... 86

Figure 5.8 - C-N 6-31G** Starting Offset Forces Fit..................................................... 87

Figure 5.9 - C-O 6-31G** Starting Offset Forces Fit..................................................... 88

Figure 5.10 - C-H 6-31G** Starting Offset Forces Fit.................................................... 89

Figure 5.11 - O-H 6-31G** Starting Offset Forces Fit................................................... 90

Figure 5.12 - N-H 6-31G** Starting Offset Forces Fit................................................... 91