COUPLING [identifier]

For a given EVB coupling method (dE-EVB or dQ-EVB, see keyword pes), this keyword gives the exact mathematical structure of the coupling term to be used.

For dE-EVB, the following terms are available:

• 1g, formula: a*exp(-b*deltaE^2)
• 2g, formula: a*exp(-b*deltaE^2)+c*exp(-d*(deltaE+m)^2)
• 3g, formula: a*exp(-b*deltaE^2)+c*exp(-d*(deltaE+m)^2)+d*exp(-f*(deltaE+n)^2)
• sp, formula: a*exp(-b*deltaE^2)+c*deltaE*exp(-d*deltaE^2)
• sd, formula: a*exp(-b*deltaE^2)+c*deltaE^2*exp(-d*deltaE^2)
• sd2, formula: a*exp(-b*deltaE^2)+c*deltaE^2*exp(-d*deltaE^2)+e*deltaE^2*exp(-f*deltaE^2)
• sp2d, formula: a*exp(-b*deltaE^2)+c*deltaE*exp(-d*deltaE^2)+e*deltaE*exp(-f*deltaE^2)+g*deltaE^2*exp(-h*deltaE^2)
• sp2d3, formula: a*exp(-b*deltaE^2)+c*deltaE*exp(-d*deltaE^2)+e*deltaE*exp(-f*deltaE^2)+g*deltaE^2*exp(-h*deltaE^2)+i*deltaE^2*exp(-j*deltaE^2)+k*deltaE^2*exp(-l*deltaE^2)

For dQ-EVB, the following terms are available:

• 1g, formula: a*exp(-b*deltaQ^2)
• 3g, formula: a*exp(-b*deltaQ^2)+c*exp(-d*(deltaQ+m)^2)+d*exp(-f*(deltaQ+n)^2)
• sd2, formula: a*exp(-b*deltaQ^2)+c*deltaQ^2*exp(-d*deltaQ^2)+e*deltaQ^2*exp(-f*deltaQ^2)

Default in both cases is 1g, which is chosen, if the keyword is not given or a nonexistent identifier is given.

The parameters a, b, c, d, ... are optimized with evbopt and stored to the evb_pars.dat file (one parameter per line, alphabetial order). This file must be given for following calculations with application programs!