First-principles calculations for the vibrational frequencies of the pentaerythritol crystal are presented, at ambient and hydrostatic pressure. The CRYSTAL03 program with the Hartree-Fock potential and B3LYP density functional were used with 6-31G and 6-31G** basis sets, respectively. The calculated OH stretching mode vibrational frequencies using this approach Lire about 200cm(-1) lower using CRYSTAL03 than those calculated using the GAUSSIAN98 program. The effect of hydrostatic pressure on vibrational frequencies is calculated and compared with experimental data, LIP to 4 GPa. The OH-stretching mode frequency decreased as a function of increasing pressure, in agreement with experiment. (c) 2006 Elsevier B.V. All rights reserved.