Ab initio calculations and reflection-absorption infrared (RAIR) spectroscopy have been used for the study of the structure and vibrational frequencies of crystalline nitric acid. The crystallographic data on the unit cell structure have been refined and the vibrational frequencies of the crystal have been determined in the calculation. A good general coincidence is found between the location of the calculated vibrational frequencies and the absorption bands in the IR spectra. Some discrepancies with previous empirical assignments are discussed. The results provide a useful base to support studies of more complex hydrous phases of nitric acid of great relevance for atmospheric chemistry. (C) 2003 Elsevier B.V. All rights reserved.