In human molecular formulas, Thims human molecular formula refers to the 26-element molecular formula for an average human, assuming the human molecular theory view, calculated in 2002, published online (Ѻ) in 2005, and in print in 2007 by American electrochemical engineer Libb Thims.
In 2002, American electrochemical engineer Libb Thims, while writing the draft chapters for a three volume Human Thermodynamics manuscript, amid writing an end chapter on cessation thermodynamics, in respect to what, at the moment a person ceases to exist (dies), constitutes the totality of a person, from a matter and energy point of view, at that moment, engaged into several months worth of research into mass composition tables and element functionality in the human, the result of which was a 26-element empirical formula version of a human, as shown below: 
Based on the empirical molecular formula, Thims was the first to specifically calculate a human molecular formula for an average 70-kg (154-lb) person, the 2008 version of which is shown below: 
Thims' calculation of the molecular formula for an average human has since become the standard textbook definition of a human, particularly in thermodynamics. 
BioNumbers | Harvard
In 2015, BioNumbers, Harvard Medical School's database of "useful biological numbers", began listing both the molecular formula and empirical molecular formula for a human, per citation of Thims (2002):
An alternative, independent, formulation is the 22-element Sterner-Elser human molecular formula (empirical only), calculated in 2000 and published in print in 2002 by American limnologists Robert Sterner and James Elser. 
1. (a) Thims, Libb. (2002). Human Thermodynamics (ch. 19: “Where Does One Go After Death”, pgs. 491-), unpublished manuscript. Chicago: Institute of Human Thermodynamics.
(b) Thims, Libb. (2002). Human Thermodynamics (Volume One), Date: Sept. Chicago: Institute of Human Thermodynamics.
(c) Thims, Libb. (2005). Cessation Thermodynamics. Institute of Human Thermodynamics.
(d) Thims, Libb. (2005). “Molecular Evolution Table” (Ѻ), HumanThermodynamics.com, Dec 13.
(e) Thims, Libb. (2007). Human Chemistry (Volume One), (preview), (ch. 2: "The Human Molecule", pgs. 15-35). Morrisville, NC: LuLu.
(f) The discovery of the Sterner-Elser calculation was a partial impetus behind the expansion of the 2007 chapter two, i.e. "The Human Molecule", of Human Chemistry, into the 2008 booklet The Human Molecule (6 Mar 2008).
(g) Thims, Libb. (2008). The Human Molecule, (preview) (Google Books). Morrisville, NC: LuLu.
2. Thims, Libb. (2008). The Human Molecule, (preview) (Google Books). Morrisville, NC: LuLu.
3. Annamalai, Kalyan, Puri, Ishwar K., and Jog, Milind A. (2011). Advanced Thermodynamics Engineering (§14: Thermodynamics and Biological Systems, pgs. 709-99, contributed by Kalyan Annamalai and Carlos Silva; §14.4.1: Human body | Formulae, pgs. 726-27; Thims, ref. 88). CRC Press.
4. Sterner, Robert W. and Elser, James J. (2002). Ecological Stoichiometry: the Biology of Elements from Molecules to the Biosphere (chapter one) (human molecule, empirical formula pg. 3; discussion, pgs. 47, 135). Princeton University Press.