Task: Text Simplification
Input (English): solid metallic hydrogen consists of a crystal lattice of atomic nuclei -lrb- namely , protons -rrb- , with a spacing which is significantly smaller than a bohr radius.
Output (English): solid metallic hydrogen consists of a crystal lattice of atomic nuclei -lrb- namely , protons -rrb- , with a spacing , which is significantly smaller than a bohr radius.