METHODS AND APPLICATIONS OF COMPUTATIONAL CHEMISTRY

What is potential energy of a system ?

Energy stored in the position or arrangement of a system, relative to other systems eg particles or its surrounding eg external fields

Equation of internal energy

U=KE+PE

What does the Born-Oppeinhemer approximation state?

It states that the nucleus is so large that the electrons ‘see’ thr nuclei as stationery, but us help up solve maths for electron behaviour

What is a Potential energy surface ?

A plot of the PE with respect to all thr molecular coordinates which represent a molecular structure

What is the reaction path?

The route lowest in energy / least resistance of R → TS → P, made up by reaction coordinates

What are the internal coordinates?

Any other coordinate not part of the reaction path, orthogonal to the PE axis

Cartesian coordinate define a single point on the PES, what do they represent and be converted into?

A molecular structure, once they are known ghey can be converted into atom position vectors, bond lengths, bond angles and dihedral angles

What are internal coordinates ?

Coordinates which if changed they would e,as to a change in energy to the molecule

Internal angle for a non-linear molecule?

3N-6

Internal angle for a linear molecule?

3N-5

What are normal coordinates?

Unique set of intern, coordinates related to normal modes of vibrations eg reaction coordinates

What is a rotamer?

Same molecule, different conformation; dihedral angles changes In order to find most favourable conformer