This utility computes some time correlation functions. For a molecular vector , the time correlation function can be determined as:
where averaging is taken over all molecules of the given type and all
acceptable initial times :
and are initial and final time of a continuous
part of the whole trajectory respectively. A trajectory is regarded as
continuous if each next configuration differs from the previous by no more
BREAKM defined in the trajectory part (
of the input file.
The program can compute the following time correlation functions:
The second Legendre polynomial TCF is defined as:
f77 -O3 -o trtcf trtcf.f tranal_base.f
Note that compilation of
trtcf.f requires, in addition to
the common header file
tranal.h, another header file
which may need to be edited in order to set array borders matching the
Input parameters for this utility follow after the trajectory parameters
in the NAMELIST block
$TCF parameter=value(s), ... $END
The following parameters are used:
FILTCF = <filename>
Defines the name of the output file
NSTEG = <int.num>
Number of time steps in the time correlation functions
DTCF = <value>
TCF time step in fs
It is recommended that TCF time step be equal to the trajectory time
step multiplied by parameter
ISTEP defined in the trajectory part
of the input. The total time of tracking TCF is
ITCF = <i1>,<i2>,...,<i12>
Flags (integers) specifying which TCF to compute (zero value - do not compute) Meanings of the flags are following:
<i1>- linear velocity of molecular center of mass
<i2>- angular molecular velocity
<i3>- dipole moment
<i4>- second Legendre polynomial of dipole moment
<i5>- a specific molecular vector (see below)
<i6>- second Legendre polynomial of a specific vector
<i7>,<i8>,<i9>- X, Y, and Z projections of the linear molecular velocity. The projections are calculated in the laboratory frame if the flags are equal to 1, and they are calculated in the principal molecular frame determined by the axis of the inertia tensor if the corresponding flags are equal to 2.
<i10>,<i11>,<i12>- X, Y, and Z projections of the angular molecular velocity. The projections are calculated in the laboratory frame if the flags are equal to 1, and they are calculated in the principal molecular frame determined by the axis of the inertia tensor if the corresponding flags are equal to 2.
N1 = <n1-1>,<n1-2>,... N2 = <n2-1>,<n2-2>,...
NTYPES values in each of the two lines, one per each molecular type.
These values specify sites (two per each molecule) which define the
molecular vector whose TCF is calculated. For each molecular type
<n2-m> should belong to it.