Preparing your input file with DEFINE

**The geometry main menu**: This first menu allows you to build your molecule, define internal coordinates for geometry optimizations, determine the point group symmetry of the molecule, adjust internal coordinates to the desired values and related operations. Beyond this one can perform a geometry optimization at a force field level to preoptimize the geometry and calculate a Cartesian analytical Hessian. After leaving this menu, your molecule to be calculated should be fully specified.**The atomic attributes menu**: Here you will have to assign basis sets and/or effective core potentials to all atoms. The SV(P) basis is assigned automatically as default, as well as ECPs (small core) beyond Kr.**The occupation numbers and start vectors menu**: In this menu you should choose`eht`to start from Extended Hückel MO vectors. Then you have to define the number of occupied orbitals in each irreducible representation.**The general menu**: The last menu manages a lot of control parameters for all`TURBOMOLE`programs.

- Universally Available Display Commands in DEFINE
- Specifying Atomic Sets
`control`as Input and Output File- Be Prepared

- The Geometry Main Menu

- The Atomic Attributes Menu
- Basis sets available
- Recommendation
- Correlation-Consistent (Dunning) Basis Sets
- Description of the commands

- Generating MO Start Vectors
- The MO Start Vectors Menu
- Assignment of Occupation Numbers
- Orbital Specification Menu
- Roothaan Parameters
- Start-MOs for broken symmetry treatments ("flip")

- The General Options Menu