The first formalism that has to be known in physics is the formalism of the motion. A formalism is associated with a certain rigorous mathematical method, defining symbols and rules that are commonly accepted, in the goal that everybody understands immediately the discussed matter. We will not be interested in the prediction of the motion nor […]

#
Posts in the *College – Main subjects* category:

# Chapter 2: quantities and units

Units are necessary to evaluate quantities. Obviously, a rhinoceros is heavier than a dog, but to know by how much, we need some reference units. Moreover, rhinoceroses don’t all have the same weight. We are thus in need of a consistent unit to measure the weight of objects. The same problem appears for all the […]

# Chapter 1: Elementary physics – Introduction

Definitions and laws “One of the noblest desire of the man is to know the laws ruling the Universe, and those who contributed to enlighten some of the mysteries were always admired by their peers; they appear as privileged, wearing on them the divine light, a through centuries the generations gaze upon their indelible work […]

# Chapter 7b : Glucose catabolism – respiratory chain

In 1935, Engelhardt analysed the rate of ATP in red blood cells (globules rouges) as a function of the rate of oxygen. The experiments showed that the ATP increases with the quantity of O2. Contrarily to the yeast, the blood cells had to be in one piece to observe the phenomenon. Even more, some enzymes […]

# Chapter 15 : MPC – Molecular degrees of freedom: vibration and rotation

In the Born-Oppenheimer approximation, we froze the position of the nuclei to find the electronic energy. The position of the nuclei was considered as a parameter that can be modified and we were able to construct the Lenard-Jones potential for the liaisons or the surface (or hypersurface) of potential energy for molecules with more than […]

# Chapter 14 : MPC – The LCAO theory

This theory says that each molecular orbital Φa is described by a linear combination of atomic orbitals {χ} centred on the M nuclei of the molecule. The molecular orbitals have the symmetry of one of the irreducible representations of the group G. This symmetry is taken into account in the LCAO coefficients. Some are null […]

# Chapter 13 : MPC – The methods of approximation and the quantic chemistry

We have seen quite a lot of new stuff up to now. We described monoelectronic and polyelectronic atoms and developed the description to molecules through the approximation of Born-Oppenheimer, the theory of groups and the CSOC. All of this teaches us how orbitals are and how they change during a reaction. Yet, we did not […]

# Chapter 12 : MPC – Orbital angular moment L

The electrons revolving on an orbital generate an angular moment. ML is the quantic number associated to the projection of L on the internuclear axis. The projection is degenerated because it can either be in the positive values of the z axis or in the negative ones. The projection of L can thus give ML […]

# Chapter 11 : MPC – Group’s theory

Because of the particular geometries of some molecules, the CSCO may be different. Instead of the CSCO that we had with the atom, we want to determine the CSCOH: the complete set of operators commuting with Ĥ. It is thus a set larger than the CSCO because the operator don’t have to commute between them. […]

# Chapter 10 : MPC – Molecules and Born-Oppenheimer

The Hamiltonian quickly becomes monstrously difficult when several atoms and electrons are considered. To illustrate this point, the equations of the Hamiltonians for H, H2+ and H2 are showed below: For a molecule with M nuclei of atomic number Z1, Z2, Z3, …, ZM and n electrons, the global expression is The Hamiltonian can be […]