1. 728345 Chapter 2 Molecular Mechanics

2. Basic Concepts Molecule: Collection of atoms held together by forces
Molecular Mechanics:
Potential Energy is described as a function of a coordinate X
Matching a function to a set of data points by varying its parameters

3. Series Expansion
The Taylor series is a representation of a function as an infinite sum of terms calculated from the values of its derivatives at a single point.
The Fourier series is a mathematical tool used for analyzing periodic functions by decomposing such a function into a weighted sum of much simpler sinusoidal component functions

4. Electrostatic Potential
Electrostatic Potential i, j are charged particles (electrons & protons)

5. Simple Molecular Mechanics Force Field
Bond-stretching
Angle-bending
Torsions

6. Bonding Stretching Taylor Expansion Hook’s Law (Harmonic Potential)
Morse Function

7. Harmonic
Taylor
Morse
req r A B
r-req

8. Valence Angle Bending
Typical force field function for angle strain energy A C q B

9. Torsions Typical force field as an expansion of a Fourier series C D B

10. j =1
j =2
j =3
j =4
Vtorsions
CH3 H w

11. Van der Waals Interactions
In the absence of a permanent charge,