QCAT

A Fortran program of Quasi-Classical Adiabatic Trajectory for collision of two molecules. (under development)

• Author : Wenbin, FAN (fanwenbin@shu.edu.cn)
• Supervisor : Yongle, LI

Intro

• Unit : atomic unit (in code)

• Language : Fortran 95

• Requirement : Intel Fortran Compiler, MKL

Usage

1. Clone all codes.
2. Connect your PES in Interface.f90.
3. Modify input file with any name.
4. Modify compiler and input file name in the Makefile.
5. make.

Note that the test case is OHCH4 system, whose PES could be obtained from Prof. Bin JIANG upon request. [ J. Li and H. Guo, J Chem Phys 143, 221103 (2015). ]

Keyword in input file

• temperature real value (K), default 298.15 K.
• ensemble NVE, NVT, Nose-Hoover thermostat
• timestep real value (fs), default 0.01 fs.
• ntraj the number of trajectories, default 1.
• nstep the number of steps in each trajectories.
• nprint print frequency of system properties.
• nxyz print frequency of trajectory.

Developing Progress

**Finished : **

1. initialize molecule
   1. remove center of mass
   2. rotate molecule to principal axis
2. initialize trajectory
   1. random rotation
   2. random thermal momentum
   3. random rotational state
   4. random vibrational state
   5. remove translational and angular momentum
3. propagate trajectory
   1. Velocity Verlet
   2. Nose-Hoover thermostat
4. interface and utilities
   1. interface to standard PES (coordinates and energy)
   2. gradient and hessian matrix, vibrational analysis
   3. pseudo-inversion of matrix

**TODO : **

1. the correctness of all kinds of momentum
2. analysis of final states and trajectory
3. treatment of ZPE