3:30 PM - 3:45 PM
▲ [19p-H113-9] Calculating the Entropy Loss on Adsorption of Organic Molecules at Insulating Surfaces
Keywords:entropy,potential of mean force,molecular adsorption
In this work we studied the effect of entropy on the adsorption energy of flexible functionalised organic molecules on an insulating KCl surface. Special attention was paid to the contribution of Van der Waals interactions to the adsorption energy.
Potential of mean force calculations were performed on 1,3,5-tri-(4-cyano-4,4 biphenyl)-benzene (TCB) and 1,4-bis(cyanophenyl)-2,5-bis(decyloxy)benzene (CDB) molecules on a KCl (110) surface. A classical force field was used to perform these calculations. In order to verify the accuracy of the force field it was tested against Van der Waals corrected DFT D2 and high accuracy MP2 calculations.
In order to understand organic systems on insulating surfaces one has to consider the free energy of adsorption at non-zero temperatures instead of the zero temperature adsorption enthalpy. For flexible organic molecules at room temperature entropy can change the adsorption energy by about 50%.
Potential of mean force calculations were performed on 1,3,5-tri-(4-cyano-4,4 biphenyl)-benzene (TCB) and 1,4-bis(cyanophenyl)-2,5-bis(decyloxy)benzene (CDB) molecules on a KCl (110) surface. A classical force field was used to perform these calculations. In order to verify the accuracy of the force field it was tested against Van der Waals corrected DFT D2 and high accuracy MP2 calculations.
In order to understand organic systems on insulating surfaces one has to consider the free energy of adsorption at non-zero temperatures instead of the zero temperature adsorption enthalpy. For flexible organic molecules at room temperature entropy can change the adsorption energy by about 50%.