His model (which was published in 1913) was a mixture of classical and quantum ideas; it also explained spectroscopic observations. In the 1920s, this model was succeeded by a fully quantum-mechanical model, which Niels also helped to create. .
In 1914, Niels was summoned back to Manchester by Rutherford to become a reader in theoretical physics, but he stayed only until 1916. The authorities in Denmark were so reluctant to lose him that they offered him a professorship and the promise of his own institute. He returned to Copenhagen, and the Institute for Theoretical Physics was established in 1918, with Niels as the first director of the institute. He remained as the director until his death in 1962, when he was succeeded by his son, Aage Bohr. The institute is now known as the Niels Bohr Institute. He made this institute into one of the world's major research centers. Scientists from all around the world came to study with Bohr. In Copenhagen, Bohr attracted most of the best theoretical physicists of the day for long and short visits. He provided so much of the stimulus for the development of ideas in quantum mechanics that the standard interpretation of quantum mechanics, which was developed by Bohr and others in the 1920s, became known as the "Copenhagen interpretation." This interpretation became the accepted explanation of quantum mechanics, and it was not seriously challenged until the 1980s and the 1990s. In 1922, Bohr received the Nobel Prize in physics for his brilliant work. Meanwhile, he had married a Danish girl, started a family, and continued teaching at the University of Copenhagen. He was sometimes so busy with his work that he forgot about his meals. Nevertheless, he always managed to make time for his wife and five sons. .
In the 1930s, the institute began important studies of the nucleus of the atom. In 1936, he made another major advance in atomic physics: he gave the first correct description of a nuclear reaction.