In this letter we present results of study of weak C-H center dot center dot center dot O=C hydrogen bonds of crystalline poly-(R)-3-hydroxybutyrate (PHB) by using Born-Oppenheimer molecular dynamics. The-polymeric structure and IR spectra of PHB result from the presence of the weak hydrogen bonds. We applied the post-molecular dynamics analysis to consider a C=O motion as indirectly involved in the hydrogen bonds. Quantization of the nuclear motion of the oxygens was,done to perform detailed analysis of the strength and properties of the C=O bands involved in the weak hydrogen bonds. We have also shown the dynamic character of the weak hydrogen bond interactions. (C) 2017 Elsevier B.V. All rights reserved.