Hi

I am doing a dimer calculation by freezing one molecule using the 6.1 version. I did S1 optimization but I got imaginary frequency in that. So I put this input taking previous optimized coordinates. In the 2 step when the molecule is optimizing, the frozen molecule is also changing its angles but I do not want that. I already gave a fixed coordinates command for the frozen molecule. So, why is this happening?

$molecule

0 3

Dimer system consists of 72 atoms

$end

$rem

BASIS = cc-pVDZ

EXCHANGE = omegaB97XD

JOB_TYPE = frequency

SCF_CONVERGENCE = 10

MAX_SCF_CYCLES = 400

MAX_CIS_CYCLES = 400

UNRESTRICTED = true

SPIN_FLIP = 1

CIS_N_ROOTS = 4

THRESH = 14

SYMMETRY_IGNORE = true

SYMMETRY = false

CIS_STATE_DERIVATIVE = 3

SOLVENT_METHOD = PCM

$end

$solvent

DIELECTRIC 32.613000

OPTICALDIELECTRIC 1.765709

$end

FIXED

37:72 XYZ

ENDFIXED

$end

@@@

$molecule

read

$end

$rem

BASIS = cc-pVDZ

EXCHANGE = omegaB97XD

JOB_TYPE = optimization

SCF_CONVERGENCE = 10

MAX_SCF_CYCLES = 400

MAX_CIS_CYCLES = 400

UNRESTRICTED = true

SPIN_FLIP = 1

CIS_N_ROOTS = 4

THRESH = 14

SYMMETRY_IGNORE = true

STS_MOM = true

SYMMETRY = false

CIS_STATE_DERIVATIVE = 3

SOLVENT_METHOD = PCM

GEOM_OPT_MAX_CYCLES = 300

$end

$solvent

DIELECTRIC 32.613000

OPTICALDIELECTRIC 1.765709

$end

FIXED

37:72 XYZ

ENDFIXED

$end

@@@

$molecule

read

$end

$rem

BASIS = cc-pVDZ

EXCHANGE = omegaB97XD

JOB_TYPE = frequency

SCF_CONVERGENCE = 10

MAX_SCF_CYCLES = 400

MAX_CIS_CYCLES = 400

UNRESTRICTED = true

SPIN_FLIP = 1

CIS_N_ROOTS = 4

THRESH = 14

SYMMETRY_IGNORE = true

SYMMETRY = false

CIS_STATE_DERIVATIVE = 3

SOLVENT_METHOD = PCM

$end

$solvent

DIELECTRIC 32.613000

OPTICALDIELECTRIC 1.765709

$end

FIXED

37:72 XYZ

ENDFIXED

$end