The interactions of glyphosate molecules with montmorillonite clay have been studied with theoretical methods, ranging from molecular mechanics to ab initio quantum mechanical calculations to explore the ways in which this herbicide may bind to the interlayer surfaces of the mineral in natural soils. Free glyphosate is moderately biodegradable, due mostly to soil microorganisms. Two pathways have been reported for its degradation in soils, one using the intermediate aminomethylphosphonic acid (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, AMPA) and the other using the intermediate sarcosine. In this work we extend the previous theoretical study of glyphosate adsorption on montmorillonite surfaces to sarcosine and AMPA. The environment of the glyphosate, sarcosine and AMPA molecules in the present calculations is the interlayer of the clay and the surrounding water molecules and cations, with a rough energy landscape. The search for the global minima is not stressed in these conditions but rather a reasonable structure for the molecules in solution determine is determined. A molecular modeling calculation was performed where the molecules were placed in the montmorillonite interlayer and were allowed to move freely, without constraints. The goal of these calculations was to establish if one of the three functional groups (COOH, NH2+ or PO3OH) is consistently closer to the montmorillonite in the final state. The final distances between atoms of these moieties and atoms of the surface are reported here for several trials with random initial configurations.