# Introduction to Quanty

This tutorial contains several files stepping through the basic ideas of Quanty when doing many body calculations. It introduces the concepts of one electron orbitals, which represent the one electron wave-functions in which electrons can go. Note that we will use the word orbital, or spin-orbital to represent both atomic orbitals, or lattice sites, or molecular orbitals or any other one electron basis set. Operators are defined in second quantization on these orbitals. Note that as shown in the first example these operators can be given as a matrix, once the Hilbert space (electron occupation) is defined. It is important to notice though that one does not need to write these operators as matrices. Calculations can be done much more efficient if one does not create the operator as matrix. Next we introduce wave-functions. Wave-Functions are given by sums over single Slater determinants, whereby each determinant is given by the occupation of certain one electron orbitals. Expectation values are given by the dot product (multiplication) of an operator with a left and right wave-function. Eigen-states are calculated by diagonalizing an operator.

After this example you should be able to use Quanty as a script language and change the examples given in this tutorial to fit your own needs. Note that not all options the script language have are well represented in the tutorials. I hope that what I present is useful to you, but I have other things to do as well. If you need to do something that you know can be done as I used it in publications, but is not here you can always ask me (Maurits) but please also realize that I can not spent all my time for you. (also note that these things then have to be done in collaborations of some sort)