Difference between 単独で and 単独に


In an online dictionary for
[単独](https://dictionary.goo.ne.jp/word/%E5%8D%98%E7%8B%AC/#jn-140459), 単独 is
used seemingly as an adverb in two example sentences, but with different
particles:

> 「単独で登頂する」 「単独に存在する」

99% of other 単独 examples online use で. Since this is a very reliable online
dictionary in my experience, what is the grammar of using 単独に here? Is 単独
treated as a different part of speech in 単独に versus 単独で?




There's definitely some freedom of choice, but で suggests agency (by whatever
is "independent"), whereas に suggests passivity/staticity. It's not by chance
that 単独で is used with 登頂する, and 単独に is used with 存在する.

Other examples I found on the Shonagon corpus:

> 『幻想交響曲』のみが 単独に コンサートで演奏される

に feels best here, since 幻想交響曲, which is what is played independently, is the
object of action. (The passive structure here is irrelevant, I would still use
に in 『幻想交響曲』を単独に演奏する.) 『幻想交響曲』を単独 **で** 演奏する, on the other hand, sounds a bit
more like "[someone] is playing it by themselves", although to me, both
interpretations are valid.

> 夫が 単独で 移住するケース

で sounds better here, since the independence describes the agent, 夫.




There's definitely some freedom of choice, but で suggests agency (by whatever
is "independent"), whereas に suggests passivity/staticity. It's not by chance
that 単独で is used with 登頂する, and 単独に is used with 存在する.

Other examples I found on the Shonagon corpus:

> 『幻想交響曲』のみが 単独に コンサートで演奏される

に feels best here, since 幻想交響曲, which is what is played independently, is the
object of action. (The passive structure here is irrelevant, I would still use
に in 『幻想交響曲』を単独に演奏する.) 『幻想交響曲』を単独 **で** 演奏する, on the other hand, sounds a bit
more like "[someone] is playing it by themselves", although to me, both
interpretations are valid.

> 夫が 単独で 移住するケース

で sounds better here, since the independence describes the agent, 夫.

