SEMIEMPIRICAL AND MOLECULAR-MECHANICS TREATMENTS OF MOLECULES

Because of the difficulties in applying ab initio methods to medium and large molecules, many semiempirical methods were developed to treat such molecules. The earliest semiempirical methods treated only the it electrons of conjugated molecules. This chapter begins with ir-electron semiempirical methods (Sections 16.1 to 16.4) and then considers general semiempirical methods (Section 16.5). 

The molecular-mechanics method (Section 16.6) is a nonquantum-mechanical method applicable to much larger molecules than semiempirical methods. 

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Chapter 16 Semiempirical and Molecular-Mechanics Treatments of Molecules... 

Chapter 16 Semiempirical and Molecular-Mechanics Treatments of Molecules The symmetry species of the benzene ir MOs are Schonland, p. 210)... 

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