gaussian基本概念和用法(12)

#P CCSD(T)/6-311+G(2d,2p) Opt

The next line should be blank (since the command line can be more than one line).

The third line is the Title. It can also be split in several lines and must be ended by a blank line. The next line gives the charge and the multiplicity of the calculation in this order.

The mulitiplicity specifies the spin state: (1=singlet=no unpaired electrons, 2=doublet, etc.). Most normal molecules are singlets.

The following lines give the geometry of the molecule. It can be specified in Cartesian coordinates (x, y, z, in ?ngstr?m), starting with the atomic symbol or number. Alternatively, it can be given as an Z-matrix (see Appendix E in Frank Jensen and the sample input below). The geometry is ended by a blank line.

The rest of the file contains additional input, is any (depending on the keywords). The file must end with a blank line. The job is started by: g98 input_file &

The output will be found in the file input_file.out.

You must specify the ampersand (\

If you run several similar calculations, it may be wise to save all important information in a checkpoint file. This is done with the line %Chk=file_name

which should be first in the file.

You can use the contents in the checkpoint file in other calculations by giving the same checkpoint file name. Guess=Read (in the command line) tells the program to read the wavefunction from the checkpoint file.

Geom=AllCheck (also in the command line) tells the program to read the title, charge, multiplicity and (final) geometry from the checkpoint file. The corresponding lines should then be ommitted from the input file. -------------------------------------------------------------------------------- Sample input files

-------------------------------- #P HF Sto-3G Opt Freq

Simple geometry optimization and frequency calculation on water 0 1

o 0.000000 0.127170 0.000000 h 0.757997 -0.508679 0.000000 h -0.757997 -0.508679 0.000000 -------------------------------- #P CCSD(T)/6-311+G(2d,2p) Opt

Geometry optimisation of water with a Z-matrix (necessary with numerical gradients) 0 1 h o,1,OH h,2,OH,1,HOH

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OH 0.9572 HOH 104.52

-------------------------------- %Chk=h2o.chk %Mem=200MB

#P MP2=RW aug-cc-pVTZ MaxDisk=2000MB Pop=(Full,NO,MK,NBO) Nosymm Compound job with more input 0 1

o 0.000000 0.127170 0.000000 h 0.757997 -0.508679 0.000000 h -0.757997 -0.508679 0.000000 ! RW 3, 0 --Link1-- %Chk=h2o.chk

#P MP2=RW aug-cc-pVTZ Pop=(Full,NO,MK,NBO) Density=Current Guess(Read,Only) Geom=AllCheck -------------------------------- %chk=PhO_VTZ

#t B3LYP/cc-pVTZ Freq(ReadFC,ReadISO) Geom=Check

Example of Freq calculations with new isotopes O (18) Phenoxyl Radical; CCL 14 Jun 2001 0 2

298.150 1.00000 12 12 12 12 12 12 18 1 1 1 1 1

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------------------------------------------------ #P B3LYP/6-31G* Scf(Conver=6) SCRF=(CPCM,Read)

Solvation calculation with non-default dielectric constant Cu+, B3LYP/6-31G*, Vacuum, E8, 21/5-01 1 1

cu 0.0 0.0 0.0 ! CPCM data EPS=4.0

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-------------------------------------------------------------------------------- Scan

This command is used to construct a rigid potential energy surface of one or more internal coordinates. The coordinates have to be specified in Z-matrix format. For the coordinate you want to scan, add after variable definition, the starting value, the number of steps -1, and the step size. Example (scan of the last dihedral): #P B3LYP/6-31G* Scan Title 0 1 h c 1 ch1 h 2 ch2 1 hch1

h 2 ch2 1 hch1 3 hch2 1 o 2 oc 1 hco1 4 hco2 1 h 5 oh 2 coh 1 hoch 0 ch1=1.093 ch2=1.101 oc =1.419 oh =0.969 hch1=108.080 hch2=108.419 hco1=106.675 hco2=112.693 coh =107.646 hoch=-180. 11 30.0

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Oniom

This is a up to three layer combined QC/MM or QC/QC method. The input is similar to a normal input, but you specify two or three different after the oniom keyword and for each atom you specify which layer it belongs to: High (first method), Medium (second method) or Low (third method), and optionally the junction replacement atoms (typically H). Most methods work with Oniom, e.g. optimizations and frequency calculations. However, SCRF does not work (it is not available for semi-empirical or molecular mechanical methods). Example: …… 此处隐藏：547字，全部文档内容请下载后查看。喜欢就下载吧 ……