Dipole Moment Calculation Plugin

Hi!

I'm an aspiring materials scientist, working on gas sensors. I'm trying to delve into organic chemistry to better comprehend the inner workings of the materials I'm using during my studies. I've recenty began learning MarvinSketch to visualize molecules and make charge related calculations.

MarvinScetch v.5.11.5 has a built-in plugin under Calculations->Charge submenu named "Dipole Moment Calculation". I'm trying out that plug-in with simple molecules, such as water, carbondioxide and carbonmonoxide.

My question is : dipole moment calculation for non-polar carbondioxide returns 0 Debye dipole moment whareas the same calculation yields 1,19 Debye for water and 2,31 Debye for carbonmonoxide. But these calculated values does not match with the literature values of 1,85 Debye for water and 0,122 Debye for carbonmonixde by a wide margin that may not me within the range of a calculation error (especially in carbonmonoxide case).

Under these circumstances I want to ask you the reason for this discrepancy between the calculated and experimental values. Am I missing a unit conversion or did I construct the molecules incorrectly? Or what else can be the underlying reason for this situation?

I attached the carbonmonoxide molecule file that I used during my calculations and visuals in MarvinSpace.

Thank you.

Hi,

thank you for calling our attention to this issue. The dipole predictor is based on the computation of partial charges. We have just checked the performance of the partial charge prediction for CO, and the results were not satisfactory as our prediction model lacked the parameter for the case of CO triple bond. One of my colleagues made an improvement in the charge computation code, so now we get a dipole of 0.26 D for the CO molecule.

However, we believe that there can be larger differences between dipole experiments and predictions for these small inorganic molecules mentioned than for standard organic molecules.

Best regards,

Csaba Fabri