Although the peptide C^αH group has historically not been thought to form hydrogen bonds within proteins, ab initio quantum calculations show it to be a potent proton donor. Its binding energy to a water molecule lies in the range between 1.9 and 2.5 kcal/mol for nonpolar and polar amino acids; the hydrogen bond (H-bond) involving the charged lysine residue is even stronger than a conventional OH··O interaction. The preferred H-bond lengths are quite uniform, about 3.32 Å. Formation of each interaction results in a downfield shift of the bridging hydrogen's chemical shift and a blue shift in the C^αH stretching frequency, potential diagnostics of the presence of such an H-bond within a protein.

The characteristics of the pnicogen bond are explored using a variety of quantum chemical techniques. In particular, this interaction is compared with its halogen and chalcogen bond cousins, as well as with the more common H‐bond. In general, these bonds are all of comparable strength. More specifically, they are strengthened by the presence of an electronegative substituent on the electron‐acceptor atom, and each gains strength as one moves down the appropriate column of the periodic table, for example, from N to P to As. These noncovalent bonds owe their stability to a mixture in nearly equal parts of electrostatic attraction and charge transfer, along with a smaller dispersion component. The charge transfer arises from the overlap between the lone pair of the electron donor and a σ* antibond of the acceptor. The angular characteristics of the equilibrium geometry result primarily from a compromise between electrostatic and induction forces. Angular distortions of the H‐bond are typically less energetically demanding than comparable bends of the other noncovalent bonds.

When PH3 is paired with NH3, the two molecules are oriented such that the P and N atoms face one another directly, without the intermediacy of a H atom. Quantum calculations indicate that this attraction is due in part to the transfer of electron density from the lone pair of the N atom to the σ* antibond of a P–H covalent bond. Unlike a H-bond, the pertinent hydrogen is oriented about 180° away from, instead of toward, the N, and the N lone pair overlaps with the lobe of the P–H σ* orbital that is closest to the P. In contrast to halogen bonds, there is no requirement of a σ-hole of positive electrostatic potential on the P atom, nor is it necessary for the two interacting atoms to be of differing potential. In fact, the two atoms can be identical, as the global minimum of the PH3 homodimer has the same structure, characterized by a P ⋅⋅⋅ P attraction. Natural bond orbital analysis, energy decomposition, and visualization of total electron density shifts reveal other similarities and differences between the three sorts of molecular interaction.

Whereas CH⋯O H-bonds are usually weaker than interpeptide NH⋯O H-bonds, this is not necessarily the case within proteins. The nominally weaker CH⋯O are surprisingly strong, comparable to, and in some cases stronger than, the NH⋯O H-bonds in the context of the forces that hold together the adjacent strands in protein β-sheets. The peptide NH is greatly weakened as proton donor in certain conformations of the protein backbone, particularly extended structures, and forms correspondingly weaker H-bonds. The PH group is a weak proton donor, but will form PH⋯N H-bonds. However, there is a stronger interaction in which P can engage, in which the P atom, not the H, directly approaches the N electron donor to establish a direct P⋯N interaction. This approach is stabilized by the same sort of electron transfer from the N lone pair to the P–H σ* antibond that characterizes the PH⋯N H-bond.

Tetrel bonds are dependent on modification of electron density and electrostatic potential caused by a substituent.