Haptic representation of the atom

Three-dimensional functions that represent atomic orbitals are traditionally difficult for chemistry students to conceptualize. Large sections of undergraduate physical chemistry texts are devoted to breaking apart and simplifying electron density functions so they can be visually represented. Traditional methodologies include skins (isosurfaces and enclosures of certain probabilities), three-dimensional projections (color, contours, slices) and two-dimensional graphs. Preliminary work with the Phantom 3D haptic interface suggests that haptics are an important addition to the chemist's tool set for representing atomic orbitals. With the Phantom, users simply move through real three-dimensional space and perceive the electron density as the force on the Phantom's pen. In our work, the force is proportional to the probability density function for the electron at any point, given by the square of the wavefunction describing a particular atomic orbital (/spl psi//sup 2/(r, /spl theta/, /spl phi/)). Nodes are felt as regions of zero force, increasing /spl psi//sup 2/ values are felt as increasing resistance, and maxima are communicated by haptic "clicks". Previous application of the Phantom to chemistry by Wanger (1998) utilized haptics for molecular docking feedback. The work tackles the altogether different problem of haptically visualizing the probability density functions of individual atomic orbitals. Feedback from chemistry students is positive and interest in continued development of the work is high among chemistry faculty.