Using Mixture of Basis Set and Pseudo-Potentials

Optimization of BBr3: This compound contains both of the light and heavy atom which indicates using just only either basis set o pseudo-potential does not computationally efficient to calculate this kind of molecule.

The important keyword for using ECP basis set:

$Functional/GEN pseudo=read gfinput

The general format of specified basis set at the end of input file is the following

charge spin.mult

coordinates

...

...

...

                                       (blank line)

atomic symbols (space) 0 (zero)

normal basis set

****                                   (four stars)

atomic symbols (space) 0 (zero)

pseudo-potential basis set

****                                   (four stars)

                                       (blank line)

atomic symbols (space) 0 (zero)

pseudo-potential

                                       (blank line)

                                       (blank line)

Example of Gaussian file of BBr3 optimization for ECP calculation

%chk=TH_BBr3_OPT_GEN.chk

# opt b3lyp/gen geom=connectivity pseudo=read gfinput

integral=grid=ultrafine

BH3 OPTIMIZATION

0 1

 B                  0.00000000    0.00000000    0.00000000

 Br                -1.74937106   -1.01000043    0.00000000

 Br                 0.00000000    2.02000000    0.00000000

 Br                 1.74937106   -1.01000043    0.00000000

 1 2 1.0 3 1.0 4 1.0

B 0

6-31G(d,p)

****

Br 0

LanL2DZ

****

Br 0

LanL2DZ

Summary

Filename = TH_BBr3_OPT_GEN.log

BH3 OPTIMIZATION

File Name = TH_BBr3_OPT_GEN

File Type = .log

Calculation Type = FOPT

Calculation Method = RB3LYP

Basis Set = Gen

Charge = 0

Spin = Singlet

E(RB3LYP) = -64.43644947 a.u.

RMS Gradient Norm = 0.00000384 a.u.

Imaginary Freq =

Dipole Moment = 0.0000 Debye

Point Group = D3H

Job cpu time:  0 days  0 hours  0 minutes 30.0 seconds.

Structural parameter

The bond distance of B-Br is 1.93396 A

The bond angle of Br-B-Br is 120 degree

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