I have been trying to follow the paper titled "Towards Quantum Chemistry on a Quantum Computer" (https://arxiv.org/pdf/0905.0887.pdf) by simulating their results on a quantum computer simulator. Unfortunately, I have been having trouble classically calculating the full configuration interaction Hamiltonian for H2 using the STO-3G basis set. In the paper they use Pyquante, but I haven't been able to find good documentation on how to use it. I would be grateful if someone could show me how to calculate this using Pyquante, point me towards better documentation for Pyquante (I've only been able to find the rather poor documentation found here: http://pyquante.sourceforge.net/), or suggest a different/free quantum chemistry program that is easier to use.

For reference, I have been using Szabo and Ostlund's "Modern Quantum Chemistry: Introduction to Advanced Electronic Structure Theory" to try to get a handle on this calculation. They come up with two single-electron molecular wavefunctions,

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where enter image description here and enter image description here are the 1S orbitals about each of the atoms.

This gives 4 molecular spin orbitals and thus 6 different Slater determinant basis states. These are the basis states for which I would like to calculate the Hamiltonian.

  • $\begingroup$ They have a cookbook with examples... pyquante.sourceforge.net/#cookbook $\endgroup$ – Buck Thorn Feb 25 at 19:52
  • $\begingroup$ If you use Mac or Linux (or Linux subsystem on windows), I would recommend Psi4. I have only used it a little, but it has CI implemented and they have pretty straightforward tutorials on Github for how to make a CI code $\endgroup$ – Tyberius Feb 25 at 19:57
  • $\begingroup$ "They" may be one too many - I am not sure pyquante is actively developed... $\endgroup$ – Buck Thorn Feb 25 at 20:12
  • $\begingroup$ @NightWriter I linked that source in my question, and (so far as I could tell) it didn't tell me how to solve my problem. Could you explain to me how I could use some of the code from the cookbook to find the full CI Hamiltonian? $\endgroup$ – Lucas Myers Feb 25 at 21:13
  • $\begingroup$ @Tyberius Unfortunately I am on a windows system. Do you have any other suggestions? $\endgroup$ – Lucas Myers Feb 25 at 21:17

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