How to obtain accurate frequencies from CP2K? (inside the post the frequencies are compared between CP2K and Gaussian)
J. Ye
jingyu... at gmail.com
Wed Nov 23 21:40:31 UTC 2016
Hi all,
I calculate frequency for small molecules and try to compare with Gaussian
09 and experimental results. I show the results from *CP2K *(PBE
functional-BASIS_MOPLOT, GTH potental, nonperiodic) and * Gaussian09 *(M062X/6-311g(d,p))
.
I have several questions:
1. You will see the total number of modes obtained from CP2K is 15, however
12 modes from Gaussian. Are the first three modes are translation modes or
rotation modes for C2H4?
2. If we only compare the 12 vibration modes, the value for most of modes
from Gaussian is larger than CP2K. What's the reason for getting smaller
frequencies from CP2K?
3. What is the keyword can strongly affect the frequencies? Affect the
accuracy of frequencies?
Thanks very much!
CP2K Gaussian
c2h4
15 modes
-19.0703
-5.64472
19.50384
807.9613 831.8134
942.954 988.1607
995.6397 996.8044
1045.988 1071.741
1206.11 1239.784
1373.488 1386.642
1446.925 1470.955
1646.778 1717.766
3158.382 3156.212
3171.654 3172.992
3269.88 3235.274
3270.754 3260.871
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