Real-space pseudopotential method for computing the vibrational Stark effect.
The vibrational Stark shift is an important effect in determining the electrostatic environment for molecular or condensed matter systems. However, accurate ab initio calculations of the vibrational Stark effect are a technically demanding challenge. We make use of density functional theory constructed on a real-space grid to expedite the computation of this effect. Our format is especially advantageous for the investigation of small molecules in finite fields as cluster boundary conditions eliminate spurious supercell interactions and allow for charged systems, while convergence is controlled by a single parameter, the grid spacing. The Stark tuning rate is highly sensitive to the interaction between anharmonicity in a vibrational mode and the applied field. To ensure this subtle interaction is fully captured, we apply three parallel approaches: a direct finite field, a perturbative method, and a molecular dynamics method. We illustrate this method by applying it to several small molecules containing C-O and C-N bonds and show that a consistent result can be obtained.
Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA.
Benjamin F
BF
Garrett
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel.
Ido
I
Azuri
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel.
Leeor
L
Kronik
Center for Computational Materials, Institute for Computational Engineering and Sciences, Departments of Physics and Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA.
James R
JR
Chelikowsky