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Is it normal to have many negative frequencies in a transition state?
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+ Computational chemistry
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Lance Chambers
Is it normal to have many negative frequencies in a transition state?
If you calculate vibrational frequency, it should be one imaginary frequency. Re optimized your structure, changing the the parameters. You can use STQN method to obtain a TS.
If you calculate vibrational frequency, it should be one imaginary frequency. Re optimized your structure, changing the the parameters. You can use STQN method to obtain a TS.
Dear Rudra Giri, Technically, A TS must contain a single imaginary frequency that pertains to the bond breaking/forming in the molecular system that you're building. (please be careful of use of terms. dont use the term "negative frequency", there is not such thing) Are there instances that a sad.search located geometry is still a viable candidate despite having more than one imaginary frequencies?... the answers are maybe, yes and no. YES - provided that it contains a single large imaginary frequency that describes the bond/breaking of your concern and all the rest are have a value less than 100 cm-1 which pertain to bending and rotation due to anharmonicities. Take note that 100 cm-1 is the threshold value that is consider to be negligible. NO - if there values were more than 100 cm-1 and others describe forming and breaking in some parts of the system that you're not concerned of... this is clearly a failure sad.search and you must start from scratch again... MAYBE - When you've obtained the "YES" criteria.. the IRC calculation has still the final say that what you're building is still valuable for a theoretical TS. CHEERS>
Dear Rudra Giri, Technically, A TS must contain a single imaginary frequency that pertains to the bond breaking/forming in the molecular system that you're building. (please be careful of use of terms. dont use the term "negative frequency", there is not such thing) Are there instances that a sad.search located geometry is still a viable candidate despite having more than one imaginary frequencies?... the answers are maybe, yes and no. YES - provided that it contains a single large imaginary frequency that describes the bond/breaking of your concern and all the rest are have a value less than 100 cm-1 which pertain to bending and rotation due to anharmonicities. Take note that 100 cm-1 is the threshold value that is consider to be negligible. NO - if there values were more than 100 cm-1 and others describe forming and breaking in some parts of the system that you're not concerned of... this is clearly a failure sad.search and you must start from scratch again... MAYBE - When you've obtained the "YES" criteria.. the IRC calculation has still the final say that what you're building is still valuable for a theoretical TS. CHEERS>
Hi Rudra, unfortunately the answer is "no, is not normal". As Martin said, a TS is characterized by only one imaginary frequency which generally correspond to the stretching of the bond (or bonds) being formed/broken. TS may also be found for conformational changes, and in this case the IF correspond to the twisting of the dihedral being evaluated. What you are observing probably depends by technical error, such as conducting the frequency analysis on a geometry optimized with a different level of theory, or by performing the analysis on a geometry far away from its energy minimum.
Hi Rudra, unfortunately the answer is "no, is not normal". As Martin said, a TS is characterized by only one imaginary frequency which generally correspond to the stretching of the bond (or bonds) being formed/broken. TS may also be found for conformational changes, and in this case the IF correspond to the twisting of the dihedral being evaluated. What you are observing probably depends by technical error, such as conducting the frequency analysis on a geometry optimized with a different level of theory, or by performing the analysis on a geometry far away from its energy minimum.
Hi Rudra , the transition state you optimized is not the actual Ts it may be a high order saddle point . TS are 1st order saddle points and should have only 1 negative frequencies.
Hi Rudra , the transition state you optimized is not the actual Ts it may be a high order saddle point . TS are 1st order saddle points and should have only 1 negative frequencies.
There should be one imaginary frequency. So, may your ts is not well optimise try to re optimize your ts structure again. put the keywords opt=ts, noeigentest, saddle=1
There should be one imaginary frequency. So, may your ts is not well optimise try to re optimize your ts structure again. put the keywords opt=ts, noeigentest, saddle=1
Dear Rudra Giri, Technically, A TS must contain a single imaginary frequency that pertains to the bond breaking/forming in the molecular system that you're building. (please be careful of use of terms. dont use the term "negative frequency", there is not such thing) Are there instances that a sad.search located geometry is still a viable candidate despite having more than one imaginary frequencies?... the answers are maybe, yes and no. YES - provided that it contains a single large imaginary frequency that describes the bond/breaking of your concern and all the rest are have a value less than 100 cm-1 which pertain to bending and rotation due to anharmonicities. Take note that 100 cm-1 is the threshold value that is consider to be negligible. NO - if there values were more than 100 cm-1 and others describe forming and breaking in some parts of the system that you're not concerned of... this is clearly a failure sad.search and you must start from scratch again... MAYBE - When you've obtained the "YES" criteria.. the IRC calculation has still the final say that what you're building is still valuable for a theoretical TS. CHEERS>
Dear Rudra Giri, Technically, A TS must contain a single imaginary frequency that pertains to the bond breaking/forming in the molecular system that you're building. (please be careful of use of terms. dont use the term "negative frequency", there is not such thing) Are there instances that a sad.search located geometry is still a viable candidate despite having more than one imaginary frequencies?... the answers are maybe, yes and no. YES - provided that it contains a single large imaginary frequency that describes the bond/breaking of your concern and all the rest are have a value less than 100 cm-1 which pertain to bending and rotation due to anharmonicities. Take note that 100 cm-1 is the threshold value that is consider to be negligible. NO - if there values were more than 100 cm-1 and others describe forming and breaking in some parts of the system that you're not concerned of... this is clearly a failure sad.search and you must start from scratch again... MAYBE - When you've obtained the "YES" criteria.. the IRC calculation has still the final say that what you're building is still valuable for a theoretical TS. CHEERS>
If you calculate vibrational frequency, it should be one imaginary frequency. Re optimized your structure, changing the the parameters. You can use STQN method to obtain a TS.
If you calculate vibrational frequency, it should be one imaginary frequency. Re optimized your structure, changing the the parameters. You can use STQN method to obtain a TS.
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Dear Rudra Giri,
Technically, A TS must contain a single imaginary frequency that pertains to the bond breaking/forming in the molecular system that you're building.
(please be careful of use of terms. dont use the term "negative frequency", there is not such thing)
Are there instances that a sad.search located geometry is still a viable candidate despite having more than one imaginary frequencies?... the answers are maybe, yes and no.
YES - provided that it contains a single large imaginary frequency that describes the bond/breaking of your concern and all the rest are have a value less than 100 cm-1 which pertain to bending and rotation due to anharmonicities. Take note that 100 cm-1 is the threshold value that is consider to be negligible.
NO - if there values were more than 100 cm-1 and others describe forming and breaking in some parts of the system that you're not concerned of... this is clearly a failure sad.search and you must start from scratch again...
MAYBE - When you've obtained the "YES" criteria.. the IRC calculation has still the final say that what you're building is still valuable for a theoretical TS.
CHEERS>
Dear Rudra Giri,
Technically, A TS must contain a single imaginary frequency that pertains to the bond breaking/forming in the molecular system that you're building.
(please be careful of use of terms. dont use the term "negative frequency", there is not such thing)
Are there instances that a sad.search located geometry is still a viable candidate despite having more than one imaginary frequencies?... the answers are maybe, yes and no.
YES - provided that it contains a single large imaginary frequency that describes the bond/breaking of your concern and all the rest are have a value less than 100 cm-1 which pertain to bending and rotation due to anharmonicities. Take note that 100 cm-1 is the threshold value that is consider to be negligible.
NO - if there values were more than 100 cm-1 and others describe forming and breaking in some parts of the system that you're not concerned of... this is clearly a failure sad.search and you must start from scratch again...
MAYBE - When you've obtained the "YES" criteria.. the IRC calculation has still the final say that what you're building is still valuable for a theoretical TS.
CHEERS>
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Hi,
your structure is not properly optimized, check input-line.
Tim
Hi,
your structure is not properly optimized, check input-line.
Tim
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Hi Rudra, unfortunately the answer is "no, is not normal". As Martin said, a TS is characterized by only one imaginary frequency which generally correspond to the stretching of the bond (or bonds) being formed/broken. TS may also be found for conformational changes, and in this case the IF correspond to the twisting of the dihedral being evaluated. What you are observing probably depends by technical error, such as conducting the frequency analysis on a geometry optimized with a different level of theory, or by performing the analysis on a geometry far away from its energy minimum.
Hi Rudra, unfortunately the answer is "no, is not normal". As Martin said, a TS is characterized by only one imaginary frequency which generally correspond to the stretching of the bond (or bonds) being formed/broken. TS may also be found for conformational changes, and in this case the IF correspond to the twisting of the dihedral being evaluated. What you are observing probably depends by technical error, such as conducting the frequency analysis on a geometry optimized with a different level of theory, or by performing the analysis on a geometry far away from its energy minimum.
More
VOTE
Hi Rudra , the transition state you optimized is not the actual Ts it may be a high order saddle point . TS are 1st order saddle points and should have only 1 negative frequencies.
Hi Rudra , the transition state you optimized is not the actual Ts it may be a high order saddle point . TS are 1st order saddle points and should have only 1 negative frequencies.
More
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Ts should have only one imaginary frequency.
Ts should have only one imaginary frequency.
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There should be one imaginary frequency. So, may your ts is not well optimise try to re optimize your ts structure again. put the keywords opt=ts, noeigentest, saddle=1
There should be one imaginary frequency. So, may your ts is not well optimise try to re optimize your ts structure again. put the keywords opt=ts, noeigentest, saddle=1
More
VOTE
Dear Rudra Giri,
Technically, A TS must contain a single imaginary frequency that pertains to the bond breaking/forming in the molecular system that you're building.
(please be careful of use of terms. dont use the term "negative frequency", there is not such thing)
Are there instances that a sad.search located geometry is still a viable candidate despite having more than one imaginary frequencies?... the answers are maybe, yes and no.
YES - provided that it contains a single large imaginary frequency that describes the bond/breaking of your concern and all the rest are have a value less than 100 cm-1 which pertain to bending and rotation due to anharmonicities. Take note that 100 cm-1 is the threshold value that is consider to be negligible.
NO - if there values were more than 100 cm-1 and others describe forming and breaking in some parts of the system that you're not concerned of... this is clearly a failure sad.search and you must start from scratch again...
MAYBE - When you've obtained the "YES" criteria.. the IRC calculation has still the final say that what you're building is still valuable for a theoretical TS.
CHEERS>
Dear Rudra Giri,
Technically, A TS must contain a single imaginary frequency that pertains to the bond breaking/forming in the molecular system that you're building.
(please be careful of use of terms. dont use the term "negative frequency", there is not such thing)
Are there instances that a sad.search located geometry is still a viable candidate despite having more than one imaginary frequencies?... the answers are maybe, yes and no.
YES - provided that it contains a single large imaginary frequency that describes the bond/breaking of your concern and all the rest are have a value less than 100 cm-1 which pertain to bending and rotation due to anharmonicities. Take note that 100 cm-1 is the threshold value that is consider to be negligible.
NO - if there values were more than 100 cm-1 and others describe forming and breaking in some parts of the system that you're not concerned of... this is clearly a failure sad.search and you must start from scratch again...
MAYBE - When you've obtained the "YES" criteria.. the IRC calculation has still the final say that what you're building is still valuable for a theoretical TS.
CHEERS>
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You can get only one imaginary frequency for the the transition state
You can get only one imaginary frequency for the the transition state
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Thank you Sir.
Thank you Sir.
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Hello,
Something it very wrong. It is hardly to say what exactly without output file.
Hello,
Something it very wrong. It is hardly to say what exactly without output file.
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