Nanotechnology offers several opportunities to solve problems related with Oil and Gas industry. One of them is the possibility to use hard nanoparticles to control the wettability phenomena between the three-phase system (oil-water-minerals) at reservoir conditions of temperature, pressure, and salinity. Here, we present a combined experimental and modeling study of hydroxylated silica nanoparticles as candidate for improved oil recovery applications. In this work, we mainly focus on development of more realistic SiO2-nanoparticle models and validating them against the experimental data. An efficient Monte Carlo scheme is proposed to generate realistic SiO2 nanoparticle atomistic models (3-5 nm). Structural and spectroscopic properties such as Raman and Infrared were obtained through Molecular Dynamics (MD) calculations using a force field that mimics an ab initio data. We have also used Fourier transform infrared spectroscopy to identify chemical functional groups present in 5 nm unmodified (bare) silica nanoparticle dispersions. A good agreement between the MD simulations and experiments has been observed.