Copyright © 2002–2007 by A. Miyoshi, Univ. Tokyo
GPOP - Quick Start step-1
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GPOP - Quick Start step-1

Followings are examples of using GPOP with sample input files, for the investigation of the vibrational modes and intramolecular rotations.

Preparation

  1. Build GPOP from source files or unpack the pre-built binaries (MS-Windows only) according to the instructions in Installation section.
  2. Set PATH to the directory where GPOP executables reside.   (Or place them in the current directory, either by copying them to current directory, or by changing directory to where they are.)
  3. Place sample input files in the current directory. (Either by copying them or by changing directory.   Note that, if you chose not to set the PATH, you must copy sample input files into the current directory where binary executables reside.)

Pre-processing

  1. Execute gpop1scf for etp500.log by typing:
    gpop1scf etp500
  2. Files etp500.gpo and etp500.mod (or etp500_.mod) must have been created in the current directory.
  3. The file, etp500.gpo, is a GPOP format file containing essential results extracted from etp500.log. A GPOP format file is an ASCII text file and may be viewed with text editors. This file only may be usefull for some purposes: for example, the value of SCFenergy key in jobInfos block is the final SCF/DFT energy at optimized geometry.

Viewing normal mode vibrations by Free Wheel

  1. Execute gpop5vib as;
    gpop5vib etp500
  2. Files named etp500_mnnn.log are generated. These files show animation of nnn-th vibrational modes when opend by Free Wheel software on MS-Windows.

Calculation of properties of an intramolecular rotation

  1. Execute gpop6irt as;
    gpop6irt etp500 8-9 1-@
  2. Calculation is made for intramolecular rotation around C[1]–O[8] bond of the ethyl peroxy radical shown below.
  3. The properties of the intramolecular rotation specified in the command line are printed to the standard output as follows:
    base file name: etp500
    moiety-1: 8-9
    moiety-2: 1-2-3-4-5-6-7
    two moieties are whole molecule.
    dihedral angle between moieties 1 and 2: 71.4081
    [moiety-1]
        appI[amuA2]: 24.05850766
        appB[cm-1]: 0.70069305
     --- symmetric top ---
     symRedI[amuA2]: 6.66957233
     symRedB[cm-1]: 2.52754274
     --- asymmetric top ---
     asmRedI[amuA2]: 7.46994390
     asmRedB[cm-1]: 2.25672767
    [moiety-2]
        appI[amuA2]: 37.50552344
        appB[cm-1]: 0.44947057
     --- symmetric top ---
     symRedI[amuA2]: -4.75414496
     symRedB[cm-1]: -3.54588033
     --- asymmetric top ---
     asmRedI[amuA2]: 7.46994389
     asmRedB[cm-1]: 2.25672767
    [most resembling vibrations]
     mode-001: 0.99820037
     mode-010: 0.53138804
     mode-004: 0.46718380
     mode-009: 0.29262286
     mode-020: 0.24449702

  4. In most cases, the required results can be found in the last of [moiety-1] section. The reduced moment of inertia for rotation around C–O bond is 7.470 amu Å2, or the corresponding rotational constant is 2.257 cm–1. Also the last [most resembling vibarations] section indicate that the rotaion around C–O bond well resembles the vibrational mode #1.

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