If you follow this course in sync with the live classes (September-December), then this chapter is your main content for week 8 of the fall term (see list of due dates).
Going thoroughly through this chapter, will take you about 2 hours (including the time spent in the exercises on this topic in ‘test yourself’.
If you have a general science background, there is no doubt you have some mental image of a chemical bond. It can be an intuitive or a sophisticated image, but at least the word chemical bond has a meaning for you. In this chapter, we will examine how DFT can increase your insight in the chemical bonds that are present in a given crystal. You will use for that purpose information based on total energies — well known to you by now, see previous chapters — as well as four-dimensional information available in electron density difference plots. How to compute the latter with Quantum Espresso code is explained in ‘test yourself’.
For sure you studied before these different types of chemical bonds: ionic, covalent, metallic and Van de Waals’ bond. Let’s refresh your memory.
Expected time: 15m
Cohesive energy is defined as the difference between the total energy of all atoms that make up a given amount of material, all of these atoms being free isolated atoms, and the total energy of the same number and type of atoms being in the crystal.
Expected time: 30m
Let’s talk about chemical bonding from DFT.
Expected time: 60m
In the preceding pages, it became clear that the simple mental picture that many of us have about the ionic bond in rocksalt is not in agreement with what DFT tells us.
Expected time: 12m
Are you still on board?
Here you can find the recording of the feedback webinar of this week.