Werner Heisenberg allotropic forms of hydrogen". Shortly after the discovery of the neutron by James Chadwick in 1932, Heisenberg submitted the first of three papers on his neutron-proton model of the nucleus. After Adolf Hitler came to power in 1933, Heisenberg was attacked in the press as a "White Jew". Supporters of "Deutsche Physik", or Aryan Physics, launched vicious attacks against leading theoretical physicists, including Arnold Sommerfeld and Heisenberg. From the early 1930s onward, the anti-Semitic and anti-theoretical physics movement "Deutsche Physik" had concerned itself with quantum mechanics and the theory of relativity. As applied in the university environment, political factors took
Heisenberg model (quantum) respectively. Other approaches do so without Bethe ansatz. The physics of the Heisenberg model strongly depends on the sign of the coupling constant formula_3 and the dimension of the space. For positive formula_3 the ground state is always ferromagnetic. At negative formula_3 the ground state is antiferromagnetic in two and three dimensions, it is from this ground state that the Hubbard model is given. In one dimension the nature of correlations in the antiferromagnetic Heisenberg model depends on the spin of the magnetic dipoles. If the spin is integer then only short-range order is present. A system of half-integer spins