Download EX3504-03

2002-03 Chem3504 Examine Paper (GH Chen)
Section A
Problem One (10 marks)
Answer true or false to the following statements and give explanations:
a. MP4 is a variation method.
b. The bond order of H2 is ½.
c. Hartree-Fock method includes all electron-electron correlation.
d. 6-31G calculations usually yield better results than 3-21G calculations.
e. DFT is a better method because it needs less computational time than Hartree-Fock
method.
Problem Two (10 marks)
a. Express the Pauli exclusion principle in the properties of many-electron wave
function.
b. How do we use the variation method to calculate the first excited state’s energy and
wave function of a molecular system?
Section B
Problem Five (15 marks)
a. Write down the Hartree-Fock equation for He.
b. Gaussian software package is a most popular quantum chemistry software in the field
of computational chemistry. Please write down an input file of a Hartree-Fock
calculation for the ground state of a CO2 molecule.
Problem Six (15 marks)
a. Explain the reason why Hartree-Fock fails for H2 when the internuclear distance is
large.
b. List three commonly used quantum chemistry methods that take into account of the
electron correlation.
c. If we want to calculate the ground state energy of a small molecule accurately and
include more than 96% correlation energy, which two methods would you
recommend?
Problem Seven (15 marks)
The chemical properties of a butadiene molecule are mostly determined by its four 
electrons. Write the Hartree-Fock equations for each of the four electrons in terms of oneelectron operator, two-electron coulomb operator and two-electron exchange operator.