## What is def2 TZVP?

def2-TZVPP – Valence triple-zeta with two sets of polarization functions. def2-TZVPPD – Valence triple-zeta with two sets of polarization functions and a set of diffuse functions.

## What is 6 31G basis set?

6-31G means each inner shell (1s orbital) STO is a linear combination of 6 primitives and each valence shell STO is split into an inner and outer part (double zeta) using 3 and 1 primitive Gaussians, respectively (see Table 11.2. 1 for other examples). Basis set.

**What is TZVP basis set?**

TZVP (triple zeta for valence electrons plus polarzation function) and DZVP should be basis sets not density functionals. TZVP is a larger basis set then DZVP. Since TZVP is a larger basis set set it should give more accurate results then DZVP but may take a long time depending on the size of the system.

### What is LANL2DZ basis set?

LANL2DZ (Los Alamos National Laboratory 2 Double-Zeta), which is a widely used ECP type basis set was used to model the metal atoms19. This mixed basis set was created through the use of the GEN keyword in Gaussian 03.

### How do you select basis sets?

Here, you can choose three different situations.

- Use different basis set for each atom in order to reduce the calculation time.
- Use the same basis set for all atom.
- Use Complete basis set extrapolation (CBS). In my opinion this is one of the best option for high accuracy calculations.

**What is effective core potential?**

Effective core potentials (ECPs) are used to replace the inner (core) electrons of atomic and molecular systems by an effective potential and treat only the valence electrons explicitly in quantum mechanical calculations.

## What is a basis set in quantum mechanics?

A basis set is a set of functions combined linearly to model molecular orbitals. Basis functions can be considered as representing the atomic orbitals of the atoms and are introduced in quantum chemical calculations because the equations defining the molecular orbitals are otherwise very difficult to solve.