How does the ambiguity of the electronic stress tensor influence its ability to serve as bonding indicator

The electronic stress tensor is not uniquely defined. Possible bonding indicators originating from the quantum stress tensor may inherit this ambiguity. Based on a general formula of the stress tensor this ambiguity can be described by an external parameter λ for indicators derived from the scaled trace of the stress tensor (whereby the scaling function is proportional to the Thomas–Fermi kinetic energy density). The influence of λ is analyzed and the consequences for the representation of chemical bonding are discussed in detail. It is found that the scaled trace of the stress tensor may serve as suitable bonding indicator over a wide range of λ values, excluding the value range between ?0.15 and ?0.48. Focusing on the eigenvalues of the stress tensor, it is found that the sign of the eigenvalues heavily depends on the chosen representation of the stress tensor. Therefore, chemical bonding analyses which are based on the interpretation of the eigenvalue sign (e.g., the spindle structure) are strongly dependent on the chosen form of the stress tensor. © 2014 Wiley Periodicals, Inc.