So, upon the addition of urea to the water-TMAO solution or the addition of TMAO in water-urea, the water density around neopentane's 1 st solvation shell is either slightly increased or decreased which depends on the nature of the TMAO's force field. water-urea-TMAO solution. Independent of the choice of the force-fields of TMAO, a slightly higher urea density in the 1 st solvation shell of neopentane is observed in water-urea-TMAO solution in comparison to that in water-urea solution. This increment is more when Netz's TMAO force field is used.