Dear Kamil, OK conversion of calorie to joule is easy, but using 1 atm standard state vs. 1 bar = 100000 Pa changes the thermochemistry. Who is really concerned for that ? Concerning the units, do you think that because books were written with calorie defined from water heat capacity in the 19th century, we should still use the corresponding unit ? (which was different from the current 4.184 J ; when I started as PhD there was 3 different "calories"...). If you still use kcal/mol when you teach, I strongly disagree, as when this unit is used in research papers. I am surprized that a young researcher adopts such a conservative position.
Dear Kamil, OK conversion of calorie to joule is easy, but using 1 atm standard state vs. 1 bar = 100000 Pa changes the thermochemistry. Who is really concerned for that ? Concerning the units, do you think that because books were written with calorie defined from water heat capacity in the 19th century, we should still use the corresponding unit ? (which was different from the current 4.184 J ; when I started as PhD there was 3 different "calories"...). If you still use kcal/mol when you teach, I strongly disagree, as when this unit is used in research papers. I am surprized that a young researcher adopts such a conservative position.
Unfortunately, Gaussian still use atm, instead of SI unit pascal (Pa) or bar. In the same vein, the standard state for thermochemistry is 1 bar and not 1 atm. Very few mention the use of 1 atm or 1 bar std state in their paper. I don't understand this policy to use obsolete units like kcal/mol...
Unfortunately, Gaussian still use atm, instead of SI unit pascal (Pa) or bar. In the same vein, the standard state for thermochemistry is 1 bar and not 1 atm. Very few mention the use of 1 atm or 1 bar std state in their paper. I don't understand this policy to use obsolete units like kcal/mol...
I tried in the same way which you have suggested. But unfortunately the job is not running and getting error. If not giving any temparature or pressure the job is running, this same input with temperature=323 and pressure=220 i have given but it is not.
I tried in the same way which you have suggested. But unfortunately the job is not running and getting error. If not giving any temparature or pressure the job is running, this same input with temperature=323 and pressure=220 i have given but it is not.
Dear Jean-Francois, the unit is just relative. Calculations in Gaussian done at 1 atm are relevant to 101325 Pa. I don't think it really matters what is the unit of calculations (neither in Gaussian nor anywhere else), as long as you report them correctly (properly recalculated from one unit to another). While now we have IUPAC recommendations - the standarized pressure unit is Pa. Historically, atm as a unit of pressure was very important in the definition of temperature. Also, please notice that IUPAC set Pa as a unit in 1982, and the first version of Gaussian was compiled in 1970. It raises further implications - changes in the code of Gaussian software (which might be difficult and confusing for users that do their research in this software for many years!), and as I said - unit is very relative, recalculations from one unit to another are discussed in general chemistry course.
Dear Jean-Francois, the unit is just relative. Calculations in Gaussian done at 1 atm are relevant to 101325 Pa. I don't think it really matters what is the unit of calculations (neither in Gaussian nor anywhere else), as long as you report them correctly (properly recalculated from one unit to another). While now we have IUPAC recommendations - the standarized pressure unit is Pa. Historically, atm as a unit of pressure was very important in the definition of temperature. Also, please notice that IUPAC set Pa as a unit in 1982, and the first version of Gaussian was compiled in 1970. It raises further implications - changes in the code of Gaussian software (which might be difficult and confusing for users that do their research in this software for many years!), and as I said - unit is very relative, recalculations from one unit to another are discussed in general chemistry course.
You can specify the temperature (in K) and pressure (in atm) in route section:
Temperature=323.15
Pressure=230
Default temperature is 298.15 K and pressure 1 atm.
You can specify the temperature (in K) and pressure (in atm) in route section:
Temperature=323.15
Pressure=230
Default temperature is 298.15 K and pressure 1 atm.
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Unfortunately, Gaussian still use atm, instead of SI unit pascal (Pa) or bar. In the same vein, the standard state for thermochemistry is 1 bar and not 1 atm. Very few mention the use of 1 atm or 1 bar std state in their paper. I don't understand this policy to use obsolete units like kcal/mol...
Unfortunately, Gaussian still use atm, instead of SI unit pascal (Pa) or bar. In the same vein, the standard state for thermochemistry is 1 bar and not 1 atm. Very few mention the use of 1 atm or 1 bar std state in their paper. I don't understand this policy to use obsolete units like kcal/mol...
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Dear Kamil Oster
I tried in the same way which you have suggested. But unfortunately the job is not running and getting error.
If not giving any temparature or pressure the job is running, this same input with temperature=323 and pressure=220 i have given but it is not.
Dear Kamil Oster
I tried in the same way which you have suggested. But unfortunately the job is not running and getting error.
If not giving any temparature or pressure the job is running, this same input with temperature=323 and pressure=220 i have given but it is not.
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VOTE
Dear Jean-Francois,
the unit is just relative. Calculations in Gaussian done at 1 atm are relevant to 101325 Pa. I don't think it really matters what is the unit of calculations (neither in Gaussian nor anywhere else), as long as you report them correctly (properly recalculated from one unit to another).
While now we have IUPAC recommendations - the standarized pressure unit is Pa. Historically, atm as a unit of pressure was very important in the definition of temperature. Also, please notice that IUPAC set Pa as a unit in 1982, and the first version of Gaussian was compiled in 1970. It raises further implications - changes in the code of Gaussian software (which might be difficult and confusing for users that do their research in this software for many years!), and as I said - unit is very relative, recalculations from one unit to another are discussed in general chemistry course.
Dear Jean-Francois,
the unit is just relative. Calculations in Gaussian done at 1 atm are relevant to 101325 Pa. I don't think it really matters what is the unit of calculations (neither in Gaussian nor anywhere else), as long as you report them correctly (properly recalculated from one unit to another).
While now we have IUPAC recommendations - the standarized pressure unit is Pa. Historically, atm as a unit of pressure was very important in the definition of temperature. Also, please notice that IUPAC set Pa as a unit in 1982, and the first version of Gaussian was compiled in 1970. It raises further implications - changes in the code of Gaussian software (which might be difficult and confusing for users that do their research in this software for many years!), and as I said - unit is very relative, recalculations from one unit to another are discussed in general chemistry course.
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