Computational Chemistry
Exam – Molecular
Modeling, Quantum
Chemistry & Study Guide
| Guaranteed success|
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales
Included
,Hartree-Fock Wavefunction Treats each electron independently
Neglect electron electron correlation
Solves one electron properties
A many electron wavefunction approximated by a product of one electron
orbitals
Population Analysis Divide up the total electron density into contributions from the individual atoms
or basic function
Each orbital is normalized
In a closed shell molecule, each occupied orbital contains 2 electrons
Each orbital is a linear combination of basis functions
Plug into the expression for the total number of electrons and rearrange the
terms
Charges from Electrostatic Potentials Charges from a least square to the electrostatic potential
What is the dipole moment for HF and DFT The expectation value of the classical expression for the dipole - can be
calculations? written in terms of the density matrix and a set of dipole integrals over a basis
function
What is the dipole moment for MPn, CI, and CC The derivative of the energy with respect to the applied field - need to
calculations? calculate the derivative of the density to get the relaxed or response density
First order properties Expressed as first derivative of the energy
Dipole and higher multipole moments
Electric field and electric field gradient
ERP - hyper fine coupling constants
Second order and higher properties Requires second and higher derivatives of the energy
Polarizability and hyperpolarizability
Force constants, vibrational frequencies and intensities
Magnetic susceptibility and NMR shielding
VCD and ROA
Potential Energy Surfaces (PES) Displays the energy of a molecule as a function of its geometry
What is the vertical axis of PES? Energy
What is the horizontal axis of PES? Geometric coordinates
, What does the equilibrium molecular structure The minima in the valleys
correspond to on a PES?
How are energetics of reactions calculated from a PES? From the energies or altitudes of the minima for reactants and products
What is a reaction path in PES? A path that connects reactants and products through a mountain pass
Where is the transition structure on a PES? The highest point on the lowest energy path
How are reaction rates obtained from a PES? The height and profile of the potential energy surface around the transition
structure
What determines the vibrational spectrum in a PES? The shape of the valley around the minimum
How is the electronic spectrum obtained from a PES? The separation between the separate potential energy surfaces of each
electronic state
What properties are given from a PES? Dipole moment
Polarizability
NMR shielding
What approximation is used for PES? The Born-Oppenheimer approximation
What are the similarities of DFT and HF? Use Born-Oppenheimer
Optimizes coefficients of orthogonal spin
Coefficients found in an iterative procedure
Need a basis sets
Can use RHF, UHF
What are the differences of DFT and HF? DFT uses electron density, HF uses one electron wavefunctions
DFT uses principle exact
HF uses insert limitations
Exchange and Correlation not defined in same way
What are the limitations to HF? Do not know the exact exchange correlation functional
The delocalization error
Self interaction error
In PES small amplitudes correspond to what? Molecular vibrations
In PES large amplitudes correspond to what? Lead to reactions
Exam – Molecular
Modeling, Quantum
Chemistry & Study Guide
| Guaranteed success|
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales
Included
,Hartree-Fock Wavefunction Treats each electron independently
Neglect electron electron correlation
Solves one electron properties
A many electron wavefunction approximated by a product of one electron
orbitals
Population Analysis Divide up the total electron density into contributions from the individual atoms
or basic function
Each orbital is normalized
In a closed shell molecule, each occupied orbital contains 2 electrons
Each orbital is a linear combination of basis functions
Plug into the expression for the total number of electrons and rearrange the
terms
Charges from Electrostatic Potentials Charges from a least square to the electrostatic potential
What is the dipole moment for HF and DFT The expectation value of the classical expression for the dipole - can be
calculations? written in terms of the density matrix and a set of dipole integrals over a basis
function
What is the dipole moment for MPn, CI, and CC The derivative of the energy with respect to the applied field - need to
calculations? calculate the derivative of the density to get the relaxed or response density
First order properties Expressed as first derivative of the energy
Dipole and higher multipole moments
Electric field and electric field gradient
ERP - hyper fine coupling constants
Second order and higher properties Requires second and higher derivatives of the energy
Polarizability and hyperpolarizability
Force constants, vibrational frequencies and intensities
Magnetic susceptibility and NMR shielding
VCD and ROA
Potential Energy Surfaces (PES) Displays the energy of a molecule as a function of its geometry
What is the vertical axis of PES? Energy
What is the horizontal axis of PES? Geometric coordinates
, What does the equilibrium molecular structure The minima in the valleys
correspond to on a PES?
How are energetics of reactions calculated from a PES? From the energies or altitudes of the minima for reactants and products
What is a reaction path in PES? A path that connects reactants and products through a mountain pass
Where is the transition structure on a PES? The highest point on the lowest energy path
How are reaction rates obtained from a PES? The height and profile of the potential energy surface around the transition
structure
What determines the vibrational spectrum in a PES? The shape of the valley around the minimum
How is the electronic spectrum obtained from a PES? The separation between the separate potential energy surfaces of each
electronic state
What properties are given from a PES? Dipole moment
Polarizability
NMR shielding
What approximation is used for PES? The Born-Oppenheimer approximation
What are the similarities of DFT and HF? Use Born-Oppenheimer
Optimizes coefficients of orthogonal spin
Coefficients found in an iterative procedure
Need a basis sets
Can use RHF, UHF
What are the differences of DFT and HF? DFT uses electron density, HF uses one electron wavefunctions
DFT uses principle exact
HF uses insert limitations
Exchange and Correlation not defined in same way
What are the limitations to HF? Do not know the exact exchange correlation functional
The delocalization error
Self interaction error
In PES small amplitudes correspond to what? Molecular vibrations
In PES large amplitudes correspond to what? Lead to reactions
