MChem Master of Chemistry Computational Chemistry 3

Question 1

In QSAR (Quantitative Structure-Activity Relationship) modeling, what are molecular descriptors?

Accepted Answer

Numerical representations of molecular features used to predict properties

Answer

3D coordinates of all atoms

Answer

Force field parameters for MD simulations

Answer

Basis functions for quantum calculations

Question 2

What is the 'zero-point energy' (ZPE) correction important for in computational thermochemistry?

Accepted Answer

It corrects for the residual vibrational energy at 0 K

Answer

It accounts for relativistic effects in heavy atoms

Answer

It removes basis set superposition error

Answer

It corrects for dispersion interactions

Question 3

In free energy perturbation (FEP) calculations, what is being computed?

Accepted Answer

The free energy difference between two states via alchemical transformations

Answer

The enthalpy difference between two states

Answer

The activation barrier using transition state theory

Answer

The entropy of a single state

Question 4

Which property does a Mulliken population analysis calculate?

Accepted Answer

Partial atomic charges from the electron density

Answer

Bond dissociation energies

Answer

Molecular polarizabilities

Answer

Transition dipole moments

Question 5

What does the acronym CCSD(T) stand for, and why is it considered the 'gold standard' in quantum chemistry?

Accepted Answer

Coupled Cluster Singles Doubles and perturbative Triples — high accuracy near the full CI limit

Answer

Complete Coupled Spectral Decomposition — exact for all systems

Answer

Configuration Cluster Singles Doubles with Triples — cheapest ab initio method

Answer

Correlated Configuration Self-consistent Doubles and Triples — used for periodic systems

Question 6

In molecular mechanics force fields (e.g., AMBER, CHARMM), what type of interactions are typically NOT included?

Accepted Answer

Quantum mechanical electron correlation

Answer

Bond stretching

Answer

Angle bending

Answer

Torsional potentials