HESSEMAT

HESSEMAT defines the Hesse matrix in Cartesian coordinates ([math]\displaystyle{ \underline{\mathbf{H}}^\mathbf{x} }[/math] ) for the use in Thermodynamic integration with harmonic reference. For a system containing [math]\displaystyle{ N }[/math] atoms, HESSEMAT has [math]\displaystyle{ (3N+1)(N+1) }[/math] lines. The first line specifies potential energy [math]\displaystyle{ V_{0,\mathbf{x}}(\mathbf{x}_0) }[/math] (in eV) of the relaxed system for which [math]\displaystyle{ \underline{\mathbf{H}}^\mathbf{x} }[/math] is computed. The following [math]\displaystyle{ 3N }[/math] lines are reserved for positions in fractional coordinates of all atoms constituting the system, whereby each line should contain three components of position vector of a single atom. The remaining part of HESSEMAT consist of [math]\displaystyle{ 3N }[/math] block of [math]\displaystyle{ N+1 }[/math] lines each. Each block contains information related to a single eigenmode of [math]\displaystyle{ \underline{\mathbf{H}}^\mathbf{x} }[/math]: the first line specified the eigenvalue (in eV/[math]\displaystyle{ {\AA}^2 }[/math]) and remaining and [math]\displaystyle{ N }[/math] lines the corresponding eigenvector (in Cartesian coordinates) in a 3-column format.

0.0
 -0.036085604 0.076532881 0.201816325
 0.039916413 -0.004546843 -0.247837560
 -0.038534014 0.141427355 0.040890125
 -0.092442988 0.033140338 0.826785057
 0.039918890 0.053102950 -0.410224011
...
11.4727211094758
 -0.114601402 0.254426349 -0.000007448
 0.334610544 0.179303391 0.000007134
 -0.102146090 -0.705453702 0.000006701
 -0.386604822 0.060633342 0.000000305
 0.268741770 0.211090621 -0.000006692

How to run thermodynamic integration calculations is given here.

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