#Hcl density pdf#

The intent is to provide illustrative examples, rather than research grade results. The examples in this paper are typically carried out at the HF/STO-3G level of theory. This approximation is generally not troublesome, but can introduce some error for systems with low lying electronic excited states.

Further, for the electronic contributions, it is assumed that the first and higher excited states are entirely inaccessible. This limitation will introduce some error, depending on the extent that any system being studied is non-ideal. One of the most important approximations to be aware of throughout this analysis is that all the equations assume non-interacting particles and therefore apply only to an ideal gas. These cross-references have the form which refers to equation 7.27 in section 7-6. I’ve cross-referenced several of the equations in this paper with the same equations in the book, to make it easier to determine what assumptions were made in deriving each equation. Much of what is discussed below is covered in detail in “Molecular Thermodynamics” by McQuarrie and Simon (1999). The equations used for computing thermochemical data in Gaussian are equivalent to those given in standard texts on thermodynamics. Enthalpies and Free Energies of Formation.Enthalpies and Free Energies of Reaction.Sources of components for thermodynamic quantities.

Gaussian thermochemistry output is explained, and a couple of examples, including calculating the enthalpy and Gibbs free energy for a reaction, the heat of formation of a molecule and absolute rates of reaction are worked out. The paper documents what equations are used to calculate the quantities, but doesn’t explain them in great detail, so a basic understanding of statistical mechanics concepts, such as partition functions, is assumed. The purpose of this paper is to explain how various thermochemical values are computed in Gaussian.

#Hcl density pdf#

Get PDF file of this paper (you may need to right-click this link to download it).