gaussian基本概念和用法(10)

Modify it by substituting atoms or groups: For example, you could change a hydrogen to a methyl group by editing the structure, replacing the desired hydrogen with a carbon atom, and then adding three additional hydrogen atoms bonded to that carbon. The latter could be given in internal coordinates: H6 1.2 2.3 1.1 H6 1.2 2.3 1.1 H7 1.2 0.0 -.9 C7 1.2 0.0 -.9 H8 0.0 -.9 0.0 H8 0.0 -.9 0.0 H9 C7 R H5 A C2 180.0 H10 C7 R H6 A C2 180.0 H11 C7 R H8 A C2 -180.0 R=1.0 A=120.0 7 2 1.5

The new structure on the right also uses an additional redundant internal coordinate (specifying Opt=ModRedundant on the final job) to alter the bond distance for the new carbon atom which is replacing the hydrogen (bonded to atom 2).

-------------------------------------------------------------------------- 13.How to carry out PES?

Relaxed PES Scans. For Opt=Z-matrix, a relaxed PES scan is requested simply by tagging the Z-matrix variables whose values are to be incremented with the S code letter and the number of steps and the increment size. For example, the following input file requests a relaxed PES scan for the given molecule: # HF/6-31G(d) Opt=Z-matrix Test Relaxed PES scan 0 1 O H 1 R1 C 1 R2 2 A2 ...

Variables: R1 0.9 S 5 0.05 R1 1.1

A2 115.4 S 2 1.0 ...

This causes the variable R1 to be incremented five times, by 0.05 ? each time, and the variable A2 to be incremented twice, by 1 degree each time, resulting in a total of 18 geometry optimizations (the initial values for each variable also constitute a point within the scan).

--------------------------------------------------------------------------- 14.How to visualize orbitals?

By default, natural orbitals are not included in the checkpoint file. Use a second job step of this form to place

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the natural orbitals into the checkpoint file: --Link1-- %Chk=name

# IOP(4/5=8,4/38=-1) Guess=(Read,Save,Only) Geom=AllCheck

Run the formchk utility on the resulting checkpoint file to prepare the orbitals for visualization. -------------------------------------------------------------------------------------- 16.Green's function ROVGF and UOVGF Keywords

These method keywords request an Outer Valence Green's Function (propagator) calculation of correlated electron affinities and ionization potentials .Use Iop(9/11=100) to specify the starting and ending orbitals to refine as input (in a separate input section with a terminal blank line). By default, all orbitals are used. ----------------------------------------------------------------------------------------- 17.How to use KMLYP

#BLYP/6-31G* Opt(Maxcycles=199) Freq

#iop(5/45=10000557) iop(5/46=00000443) iop(5/47=04481000)

------------------------------------------------------------------------------------------ 18.How to output the Fock Matrix and Overlap Matrix? Fock Matrix : iop(5/33=3)

Overlap Matrix : iop(3/33=1)

I am calculating a system consists of 3 gold atoms and 1 sulfer atom. (Originally, there should be more carbon and hydrgon to follow, but since I can not even get convergence on this simple system, I didn't go further.)I am using a LANL2DZ basis set for 3 gold atoms and 6-31G(d) for sulfer atoms.(I have tried adding SCF(MaxCyc=200),still doesn't work)However, the job terminates with the following error:(I am using Gaussian98RevA.11.2)Anyone has any idea what is wrong? help me out, please! .......

of initial guess= 0.7500

Requested convergence on RMS density matrix=1.00D-08 within 64 cycles. Requested convergence on MAX density matrix=1.00D-06. Virtual orbitals will be shifted by 0.200 hartree. Defaulting to unpruned grid for atomic number 79. Restarting incremental Fock formation. Restarting incremental Fock formation. Restarting incremental Fock formation. >>>>>>>>>> Convergence criterion not met.

SCF Done: E(UB+HF-LYP) = -804.520113362 A.U. after 65 cycles Convg = 0.8395D-06 -V/T = 2.5258 S**2 = 0.7554

Annihilation of the first spin contaminant: S**2 before annihilation 0.7554, after 0.7500 Convergence failure -- run terminated. Error termination via Lnk1e in

/afs/ir.stanford.edu/class/chemeng444a/programs/gaussian/sun4x_58/g98/l502.exe.

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Job cpu time: 0 days 0 hours 27 minutes 37.1 seconds. Here is my input file. #gfinput iop(6/7=3)

# b3lyp/gen opt(modredundant,maxcycle=200) Pseudo=Read Title Card Required 0 2 Au

Au 1 2.884000

Au 1 2.884331 2 60.003801

S 3 2.108711 1 46.856789 2 57.247633 1 B 2 B 3 B * F Au 0 LANL2DZ **** 4 0 6-31g(d) **** Au 0 LANL2DZ

Responses: ---------------------------------------------------------- Uwe Richter

well, you might get your calculation converged within the next hundred cycles. Sometimes it just takes a lot of iterations. Other programs might converge faster. You could also run a ROHF calculation first and use the resulting MOs as starting vectors via guess=read, but there is no warranty that this works (but it's worth trying). Uwe

---------------------------------------------------------- wangd

In my opinion, first, please check if the structure is reasonable; second, you may add the keyword of scfcon=5(which decrease the scf convergence) to the path. It should work. Good luck! Best wishes, Wang Dongqi

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Laurence Cuffe

># b3lyp/gen opt(modredundant,maxcycle=200) Pseudo=Read

Try this as #b3lyp/gen opt(modredundant,maxcycle=200) Pseudo=Read SCF=(maxcycle=400,vshift,sleazy) >

Let this run for a few optimization cycles and then remove the keyword sleazy. What this does is it a …… 此处隐藏：3733字，全部文档内容请下载后查看。喜欢就下载吧 ……