The following exercises are to be completed in the computational
laboratory and reports handed in to Miss Lisa Benbow in 442
on the dates indicated. Work submitted late will be penalised.
The maximum number of figures allowed in your report is 20.
Note that during scheduled sessions the computational laboratory is reserved solely for your use.
Group B: 18th January to 22nd January;
deadline 13:00 on Wed 27th January. (Postponed due to network problem)
Group A: 22nd February to 26th February;
In each exercise there are a number of explicit Questions and often also an opportunity to Speculate on the results obtained. The final report will be expected to contain answers to these questions and, where you feel able, further speculation.
Questions related to this computational experiment can be directed
Prof. Nicholas Harrison
and Dr Giuseppe Mallia.
The aims of this lab are
The hydrogen chain is hypothetical, since this system is unstable and will dissociate forming hydrogen molecules. This is also the reason why the word "cluster" has been adopted for the systems with more than 2 atoms. Nonetheless, the hydrogen chain and the considered clusters result to be a good set of models for understanding band structure.
Once the hydrogen chain is reached, there will be an extention of the periodicity, from 1 to 2 dimensions, the slab/layer, and from 2 to 3 dimensions, the hydrogen crystal.
The concept of density-of-states (DOS) will be also introduced. A DOS is a way to group levels according to their energy value. Then, the DOS curve counts the levels and is a function of the energy. The integral of the DOS from the energy of the lowest occupied orbital to the highest occupied orbital gives the total number of occupied molecular orbitals (MOs) for a molecule ( or a finite system) and the number of occupied crystalline orbitals for a solid (or a infinite periodic system).
Linux provides an excellent environment for numerical simulations so the first step is to reboot your computer into RedHat Linux.
The environment is not hugely dissimilar to that provided by Microsoft Windows. You will find a web browser (Mozilla) on the tool bar and under the Start Menu you will find some office tools (Writer, Math etc.) which are similar to those in Microsoft Office (Word, Excel etc.) and you may find them useful in plotting your data and writing your report.
DLVisualize is a general purpose graphical user interface for modelling. It will give you relatively easy access to a number of quantum mechanical and empirical simulation codes. In this case the interface to the code CRYSTAL.
The CRYSTAL program computes the ground state energy, electronic wave function and properties of periodic systems within Hartree Fock, density functional or various hybrid approximations, will be used.
There are web sites devoted to both DLV and CRYSTAL where you can find some additional information.
Further information about DLV
Further information about CRYSTAL
How to start DLVisualize
How to save a picture for your report