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The deuteron: numerical bound-state solution

A program describing the deuteron as a proton–neutron bound state with both s-wave and d-wave components, computing its properties from the wave function.

2nd place, Open Science conference 2024

Where
Open Science internship, Institute of Physics of the Czech Academy of Sciences
Supervisor
Ing. Martin Schäfer, Ph.D.
When
01/2024 – 11/2024

The deuteron is the simplest nucleus. The tensor part of the nuclear force mixes the s-wave (l = 0) and the d-wave (l = 2), so the radial Schrödinger equation becomes two coupled equations.

I implemented a matrix Numerov method for coupled channels with a realistic potential (central, tensor and spin–orbit parts). The binding energy is found by matching the outward and inward solutions; the normalized wave function then gives further properties of the deuteron.

During the internship I also applied the methods to nucleon–nucleon scattering phase shifts and to quarkonium (exotic meson) spectra.

  • u(r): s-wave (l = 0)
  • w(r): d-wave (l = 2)

EB = −2.23 MeV (experiment −2.2246 MeV) PD ≈ 6.5 % rrms ≈ 1.92 fm Q ≈ 0.274 fm²

Radial wave functions of the deuteron from my coupled-channel Numerov code, normalized so that ∫(u² + w²) dr = 1.

Key results

  • Binding energy −2.23 MeV (experiment −2.2246 MeV)
  • Wave function with s- and d-wave components
  • D-state probability P_D ≈ 6.5 %
  • RMS radius ≈ 1.92 fm (experiment 1.97 fm), quadrupole moment Q ≈ 0.274 fm² (experiment 0.286 fm²)