MChem Master of Chemistry Computational Chemistry

Question 1

Which method uses the Born-Oppenheimer approximation to separate nuclear and electronic motion?

Accepted Answer

Ab initio quantum chemistry

Answer

Molecular mechanics

Answer

Monte Carlo simulation

Answer

Molecular dynamics

Question 2

In density functional theory (DFT), the exchange-correlation functional approximates which quantity?

Accepted Answer

Many-body exchange and correlation effects

Answer

Kinetic energy of electrons

Answer

Nuclear repulsion energy

Answer

Electrostatic Coulomb energy

Question 3

What is the primary advantage of the B3LYP hybrid functional in DFT calculations?

Accepted Answer

It combines exact Hartree-Fock exchange with DFT correlation for improved accuracy

Answer

It uses no empirical parameters

Answer

It eliminates basis set superposition error

Answer

It is exact for multi-reference systems

Question 4

In molecular dynamics (MD) simulations, what does the NPT ensemble maintain constant?

Accepted Answer

Number of particles, pressure, and temperature

Answer

Number of particles, volume, and temperature

Answer

Energy, volume, and temperature

Answer

Number of particles, energy, and pressure

Question 5

Which basis set type uses Slater-type orbitals approximated by Gaussian functions?

Accepted Answer

Pople-style split-valence basis sets (e.g., 6-31G)

Answer

Plane-wave basis sets

Answer

Numerical atomic orbital basis sets

Answer

Natural bond orbital basis sets

Question 6

What does the term 'basis set superposition error' (BSSE) describe in computational chemistry?

Accepted Answer

Artificial lowering of energy when fragments share basis functions

Answer

Error from truncating the Hamiltonian operator

Answer

Inaccuracy in computing nuclear repulsion

Answer

Error from using an incomplete exchange-correlation functional