Quantum Mechanics

Object Oriented Programming

One Potential Solution

This is the solution the MolSSI team decided. Your team may decided to implement something different.

  1. The Noble_Gas_Model class. The Noble Gas model is a data class. It has data associated with the noble gas model, and utility functions for indexing.

    The Noble Gas model class is initialized with a gas type.

    The Noble_Gas_Model class has the following attributes.

    • model_parameters A dictionary of the parameters for a specific noble gas. You already have the parameters for Argon.

      You can also add paramters for Neon.

       {
         'coulomb_p': -0.010255409806855187,
         'coulomb_s': 0.4536486561938202,
         'dipole': 1.6692376991516769,
         'energy_p': -3.1186533988406335,
         'energy_s': 11.334912902362603,
         'r_hop': 2.739689713337267,
         'r_pseudo': 1.1800779720963734,
         't_pp1': -0.029546671673199854,
         't_pp2': -0.0041958662271044875,
         't_sp': 0.000450562836426027,
         't_ss': 0.0289251941290921,
         'v_pseudo': -0.015945813280635074
 }

      The rest of the attributes are general for every noble gas.

    • ionic_charge
    • orbital_types
    • p_orbitals
    • orbitals_per_atom
    • vec
    • orbital_occupations

    The Noble_Gas_Model class has the following methods (indexing functions)

    • atom
    • ao_index
    • orb

This class is an example of the builder pattern.

  1. The Hartree_Fock class The Hartree Fock class performs the Hartree Fock calculation. It is initialized with atomic_cooridnates, and a Gas_Model object.

    The Hartree_Fock class has the following attributes.

    • atomic coordinates
    • gas modle
    • ndof (number of degrees of freedom)
    • interaction matrix
    • density matrix
    • chi tensor
    • hamiltonian matrix
    • fock matrix

    The Hartree_Fock class has the following methods.

    • calculate_interaction_matrix
    • coulomb_energy
    • calculate_potential_vector
    • calculate_chi_tensor
    • chi_on_atom
    • hopping_energy
    • calculate_hamiltonian_matrix
    • pseudopotential_energy
    • calculate_atomic_density_matrix
    • calculate_fock_matrix
    • calculate_density_matrix
    • scf_cycle
    • calculate_energy_ion
    • calculate_energy_scf
    • solve Performs scf cycle.

  2. The MP2 class The MP2 class inherits from Hartree_Fock.

    The MP2 class is intialized with atomic coordinates and a gas model object.

    The MP2 class has the following additional attributes.

    • hf_energy
    • occupied_energy
    • interaction_tensor

    The MP2 class has the following additional methods.

    • partition_orbitals
    • transform_interaction_tensor
    • calcualte_energy_mp2

    The MP2 also has a solve method. It must first run Harteee Fock, then do some additional work to solve MP2. Since the MP2 class inherits from Hartree_Fock, you can use super() to inherit everything from the Hartree_Fock solve. Then you can add code for doing MP2.

challenge - The way the MP2 method is currently implemented, an MP2 object will always have to first run Hartree Fock. Can you figure out a way to initialize the MP2 class with a Hartree Fock object? (we haven’t taught you this)