Structure of crystalline methanol at high pressure

We have determined the crystal structure, including all atomic positions, of methanol at high pressure and room temperature by a combination of x-ray diffraction experiments and ab initio pseudopotential calculations. The structure has triclinic P (1) over bar symmetry with six molecules per unit cell. The molecules form strained hydrogen-bonded chains in a unique sequence of molecules in a two-parallel and one-antiparallel arrangement. This complex structure reveals that at high pressures, hydrogen bonding is important relative to repulsive forces, and may explain the glass forming capabilities of this simple alcohol. [S0163-1829(98)50442-0].