Partition functions

Generation of partition funcitons

A partition functions can be computed on a grid of temperatures using the block partfunc, which specifies the temperature grid via Tmax (maximal temperature) and N (the number of the temperatures).

Example:

partfunc
 N     500
 TMax  5000.0
end

output    ScH_adj_16665
States    ScH_adj_16665.states

Different moments (1,2,3) can be computed as follows

Example:

partfunc
 N     500
 TMax  5000.0
 moment 1
end

output    ScH_adj_16665
States    ScH_adj_16665.states

Alternatively, the temperature grid can be given as TEMPERATURE-LIST, see the corresponding documentation. The structure of the input in this case is as follows:

partfunc
  list
end

temperature-list
 200
 296
 300
 1000
end

where the keyword list is used to indicate the temperature will be read from a temperature-list.

Specific heat

partfunc
 Ntemps     500
 tempmax  5000.0
 Cp
end

Keywords:

• N, Ntemp or Npoints is the number of temperature steps

• Tmax, tempmax, Maxtemp or Max-Temperature is the maximal temperature in K (minimal T = 0K )

• Moment (0,1,2, or 3) is the moment to compute, 0 is the partition function (default and can be omitted), 1 is the 1st moment, 2 is the 2nd moment and 3 is CP.

• CP is equivalent to Moment 3

Providing partition external function functions

An single partition function value can be defined using the keyword pf:

pf 3817.0

Alternatively, a file containing a partition function on a grid of temperatures (assuming the standard format, \(T\,\,\,\,\,Q(T)\)) can be provided using the keyword pffile, e.g.

pffile  28Si-16O__SiOUVenIR.pf