Basis Sets

A good primer for Basis Sets can be found in most Computational Chemistry books or websites, and even in Chapter 12 of the P-Chem textbook (Quantum Chemistry, 2nd ed., McQuarrie). The larger the basis set, the longer the calculation will take. Generally speaking larger basis sets are more accurate than smaller ones, but this is not always the case. For example, if you don't have any anions, diffuse functions might make the results worse.

1. 6-311g* works well for most organic systems if the hydrogens generally don't do anything. Otherwise you should add another polarization function, i.e., 6-311g**.

2. LACVP works decently for molecules containing transition metals.

3. You need diffuse functions for anions. (These are indicated by + signs in a basis set.)

For basis sets not available as a default in Jaguar, you can go to the EMSL Basis Set Exchange. Refer to the Jaguar manual (Chapter 10) to figure out how to use these in your input file.